I think Sasori is immune to most Genjutsu, including Tsukuyomi. Sasori's only human part is his heart, nothing else. I think Itachi will be forced into Susano'o. Yata Mirror will work from the front, but the puppets can get him from behind. I know that the puppets will not get past Susano'o from the front or from the back, but that's not the point. It would wear Itachi out, being constantly bombarded by puppets from all sides. And eventually Itachi's eyes will give out from so much stress. It's like a fat man being attacked by a swarm of bees. The fat man is stronger but eventually he will get tired, while the bees are still going.
There are 298 puppets in Sasori's possession, it will be very hard to stab Sasori in a swarm of hundreds of very deadly puppets.
But if Itachi makes the most of Susano'o, I see him coming out on top.