Her father rules Wutai. In the English version of the game, the people in the pagoda call her "Miss Yuffie", but I'd be willing to bet they originally called her "Yuffie-sama". (Be nice if someone could source that, but hey.) While it's still not "Yuffie-hime", I think it's pretty obvious she's considered royalty of SOME sort. Personally, I think the whole "well no one ever outright calls her Princess or Godai King/Emperor/etc." to be rather silly... Godai rules over the single town we see of Wutai. To say that he's not an Emperor or whatever and thus Yuffie a princess just because it's never stated in those exact terms would be like saying that Shinra actually has little power outside of some manufacturing, energy production, and hiring out guards, even though it's pretty plain to anyone that's played the game that they run everything. -