Allow me to quote Dan Piraro from an old VegNews magazine:
As an Italian American, I know a little about pizza. My grandparents immigrated to America from Sicily at the turn of the century with little more than the clothes on their backs, too many children and a pizza recipe. I grew up eating my grandmother's pizza — real Italian pizza — and guess what? It didn't have cheese on it. Yes, you read that correctly — Italian pizza does not always have cheese. Furthermore, it doesn't always have meat, either.Anyhow, they only wish that *their* cheesy pizzas were this good. It was loaded with zucchini, mushrooms, olives, artichokes, peppers, 'homemade' seitan, and some fennel. It isn't yet baked in the foto, of course. Really, we would recommend using slightly fewer toppings in order to bake everything well into the middle — but once you start, it's hard to stop!
In conclusion: yes, vegans eat pizza. :)