Itachi Wins, logically itachi would dominate kakashi. itachi's mangekyo is very powerful with amaratsu, susanoo, and tsukiyomi. kakashi's mengkyo is to open a portal to whatever he is looking at but each time he uses it, it almost kills him cause he's not an uchiha.
so itachi can just be standing there using tsukiyomi on kakashi, and while kakashi is dealing with that itachi will burn with with amaratsu then slice him in half with his susanoo. Even if kakshi manages to escape somehow, Kotoamatsukami Pwns Him. But I think If Kamui succeeds, Kakashi wins, Itachi wins tho nvm ._.