Yes. Bolas's Citadel's first ability says "You may look at the top card of your library any time" (as opposed to, say, "any time you could cast an instant" [C.R. 304.5]), including while a spell such as Ad Nauseam is resolving. Notably, in this scenario, you may look at the next top card of your library immediately after you put a card into your hand and before you lose life equal to that card's converted mana cost. See also this thread.
Bolas’s Nauseam