Of course Nagato takes this.
None of Itachi's attacks are able to hit him, due to the 6 paths power, while Itachi doesn't have any counters to Chibaku.
Itachi's offensive jutsu/Nagato's counters:
Amaterasu/Shinra Tensei
Genjutsu/All of Itachi's Genjutsu requires eye contact, or through his ring. Nagato knew Itachi for a long time, and being as experienced as he was, he'd know better than to look into the eyes of an Uchiha, and in Itachi's case, he'd probably just close his eyes. His sensory abilities would be agreat help in fighting Itachi's Genjutsu.
Fire Release/Preta Path, Shinra Tensei
Water Release/Preta Path, Shinra Tensei
Susanoo/Itachi's Susanoo was strong, but not strong enough to handle Nagato's attacks + Gedo Mazo + Animal Summons all at once, especially when we consider the fact that Itachi had below average stamina.
Taijutsu/ Human Path, Asura Path, Deva Path
Weapon techs/Asura Path, Deva Path
Itachi however, can't handle Chibaku, and would probably even lose to Nagato without him using the Chibaku Tensei, considering the fact that Nagato's attacks/defensive tehs are a very difficult matchup for Itachi
Nagato takes this, the only way Itachi is going to win is if he has enough teammates on his side, is extremely lucky, or somehow manages to surprise Nagato and catch him in a Genjutsu