I can find no source which indicates that Gabe Saporta is vegan but plenty which indicate that he is vegetarian.
If you have a source which indicates that he is vegan, please share it with us. Thank you :)

Gabe is not vegan.He's veggie. He did a Canadian interview last year and the host gave him cheese. She gave it too him because he made a list of things for fans to bring him and cheese was one of the many dairy products on the list.

GABE ROCKS!!!!

P.S. Cobra Starship rocks

Gabe mentioned in an interview that he is in fact vegan.