OL wrote: It's pronounced "Zillia." They say it in the Japanese trailers and whatnot, and that's how it sounds (well, more like "shillia," but that's just an accent issue). The IGN guy is just a dummy (surprise!).
EDIT: Of course, just to be fair, he does say "Zillia" when he shows the cd, then corrects himself and says "ex-illia."
So maybe he thought it was Zillia initially, but the Namco translators screwed it up or something. Hard to say until we actually get it.
I posted a video on the last page shown below in spoilers, its a E3 video and a guy from namco was there showing the game and he pronounces it ex-illia, thats why I am like... wtf? but x makes a z sound when its used like that. I have been saying zillia idk
edit - wait scratch that lets just call it cross-illia instead