@bisonhero: Both of you. For all intents and purposes, the Sheik persona is supposed to be male. However, Sheik is obviously still Zelda at the end of the day whether or not she is disguised as a dude.
This question is less about what pronoun should be used and more about the specific lore stuff. It's been a long time since I played Ocarina of Time, so I don't remember, was the purpose of the Sheik disguise to hide the fact that she's a woman in order to do "unladylike" stuff like fighting (in other words, Mulan)? Or was it just to hide the fact that she's Princess Zelda in order to keep a low profile and evade Hyrule royal guards?
I always assumed the latter, that Sheik was "inconspicuous commoner vs high profile royal target" rather than "man vs woman". But again, I haven't played OoT in like 15 years.