Hashirama has been fighting Uchiha all of his life. I'm sure he knows how to deal with genjutsu.
Assumption, but it's a fair assumption... still, lets go with it.
There's nothing implying that he knows how to deal with Genjutsu on Itachi's calibre. His Tsukuyomi is quite different, it's of a very high level - He controls space and time itself. According to Kakashi, quite an adept Sharingan user himself there's no cancelling the effects of it.
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It's stated by the user himself that only someone of his blood and the Sharingan can defeat him
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For arguments sake, lets assume he CAN break it... it still won't help him. 1 second in the real world = 3 days in Itachi's world. He won't even realise he's in a MS Genjutsu in one second, much less break it.
Also, Hashirama won't be "tanking" it just in case that argument comes up. His physical energy and life force from Asura and the Senju is irrelevant, it's not physical injuries he'll be suffering, it's mental injuries.