Eu acho que ele seria capaz de resistir e as Horcruxes não terão efeito, pois são usadas apenas para alcançar a imortalidade.
De acordo com o Harry Potter wiki,
Resisting the Imperius Curse is possible, but requires great strength of will and character. The fact that it can be resisted makes it unique amongst the Unforgivable Curses as it is the only curse that has a manner of defence. Harry Potter, Barty Crouch Sr. and Barty Crouch Jr. each learned to resist the curse after being subjected to its effects, though the latter two took quite a long time before building the said resistance, and in Barty Sr.'s case, resistance against Voldemort's powerful curse has seemingly caused mental damage. Resisting the Imperius Curse is similar to Occlumency, which requires a great amount of willpower, though it is unknown if Occlumency would actually work against the curse.