My colleagues at work make wise cracks about me being like Toula's dad, because of all my crackpot Greek etymologies -- remember, I once even argued that "fudgepacker" is Greek for "bound by the will of the Gods" (
http://www.behindthename.com/wwwboardarc/messages/5870.html)
I am quite intrigued that the movie had such a success in the States. Its probably because -- as you said -- it appealed to many an ethnic family :) In Greece it was actually a flop -- more people saw "Charlie's Angels".
To answer your question, Phortoula is not a bonafide name nor an alternative spelling of Photoula in mah neck of the woods -- probably one reviewer got it wrong and everyone else followed suit.