Yoo-fi? Yoo-ef-ee?
They shoulda made it easier to pronounce if they wanted people to call it that
The character is Yuffie Kisaragi from 'Final Fantasy VII', a JRPG game for PS1 from 1997 with astonishing staying power. I'm guessing the recent-ish quasi-remakes for PS4 have something to do with that, but FF7 has been in popular culture for the last thirty years pretty much non-stop.