Is there a way to add symbol fonts in italic?

Some questions to check, please note your answers here as you go through them:

What kind of document is it? A pdf, perhaps?
Are the fonts embedded in the file (if you don't know how to find that out, just let us know)?
Which font does it use for the greek letters?
Is the font available for use in Inkscape?
Have you installed the font on your computer?
Is it available for other programs? (e.g. Word or LibreOffice)

Please share a document that you're trying to import (you need to upload it to a file hoster, like google drive, dropbox or framadrop and share a link here in your comment)

Thanks for replying. The document is a figure I created in PowerPoint, which contains Greek math symbols, which were themselves created by a program called MathType. The fonts used by MathType are italicized Symbol fonts. I am not sure if the fonts are embedded or not. I tried to convert the figure into various formats, such as .emf or .wmf. For example, an .emf looks fine when opened with Microsoft Paint, but Inkscape cannot import it (a link to this test file is here: https://www.dropbox.com/s/e1m55chsy7l1rw5/test.emf?dl=0). On the other hand, the .wmf version can be opened, but the fonts are all wrong. I think the problem is that italicized Greek fonts do not appear to be available in Inkscape. I am running Inkscape version 0.92.2 on a Windows 10 machine.
Thanks for helping!

When I open the linked file on my Linux system with Inkscape 0.92.2, I get the following result:
http://i.imgur.com/SUaKheG.png

It opens. The greek letters are set in italic. Their font is Times New Roman (in my Inkscape).

The drawing isn't very clean after import, it contains lots of invisible white rectangles (one for each letter) and so forth.

To pinpoint why you cannot open the file, can you please tell us which error message you get?
Also, if you know how, please open the command line and enter:
inkscape C:\path\to\your\testfile.svg

(replace the path by the correct one)
Then paste the error message that it prints out on the command line here.

As a temporary workaround, could you try to export to pdf from PowerPoint? Or maybe even to SVG, if that format is offered? eps or ps would also be good.

Ah ha. Well at least you can open the file. The error message I get is "Inkscape encountered an internal error and will now close".

On the other hand, I can open a .wmf file, and the result looks the same as what you obtained. In other words, the fonts are garbled. It seems Inkscape is switching the fonts to Times New Roman by default, because it does not have the correct italicized Greek fonts.

To see what the figure should look like, you could try opening it with another program such as Microsoft Paint or Irfanview (I'm not sure what Linux has to offer).

I tried the command line you suggested but got as a response:
'inkscape' is not recognized as an internal or external command, operable program or batch file

As for a temporary workaround, Powerpoint does not offer to save figures in vectorized formats. Ultimately I would like to convert my figure to .eps, and I'm trying to get Inkscape to do this, unsuccessfully.

Actually, I'm writing a book, and I have 150 such figures. So I am really eager to find a solution!

Ah, so that's the goal :)

Try inkscape.exe instead, or enter the path to the .exe file to hopefully get a useful error message.

Is it possible to open the powerpoint files with libreoffice? I think that should be able to export to useful file formats.
Or can you just do a 'print to file'? That should produce a pdf or ps file (at least, I can choose between the two). Can't tell you if they'll be in vector format, though (they should, but well...)

I cannot open the emf file in any image app, but LibreOffice opens it (looks like this: http://i.imgur.com/rYYRHJ4.png), I'd need a screenshot for comparison - there's a reason it's called 'enhanced Windows metafile' ;-)

Else, there are a couple of emf to svg convertors to be found online - have you tried any of those?

Or perhaps your goal is this:
https://www.cs.bu.edu/~reyzin/pictips.html (How to Convert PowerPoint Pictures for Use in LaTeX) - then better follow that guide :)

I think I may have found a way. I first use Irfanview to convert .emf to .pdf. I can then use Inkscape to convert .pdf to .eps. It's roundabout, but it seems to work. Phew!

Still, it seems that Inkscape may have a bug in that it does not support italic Greek fonts. For the record, the correct figure looks like this: https://www.dropbox.com/s/i5frd6y1hqo5rx5/test.pdf?dl=0

I think .svg must be a Linux format, because this format never pops up on any of my menus.

The last website you recommended was a good one, but all the techniques they listed to directly convert to .eps failed the same way Inkscape failed. But it was definitely worth a try.

In the end, I think it's a Windows problem. For some reason, it doesn't seem to treat italic Greek fonts the same way as other fonts, and this has repercussions on all the programs under this system.

Anyway, looks like I'll go with the Irfanview->Inkscape solution.

Thanks so much for your help....

Mmh, the letters look the same for me in every screenshot I made (be it Inkscape or Libreoffice, or your pdf upload now - http://i.imgur.com/cUVbBMK.png). What doesn't work with Inkscape or LO is the vector arrows above the letters, but the letters are italicized, and they are Greek. Do they look different for you?

SVG is a standardized vector graphics file format, mainly intended for use on web pages. It is standardized by the W3C, the same organization that is responsible for HTML. If you want to look at an SVG, use a web browser - Chrome or Firefox or even Edge. Your other programs probably don't save to it because they do not produce vector data (or because they do not care about standards and promote vendor lock-in).

Yes, Irfanview is a great tool, I used it a lot when I was still a Windows user. Glad you found a solution!