Has Goku ever hit Chichi?

Not unless this counts, when he and Gohan came out of the Hyperbolic Time Chamber and talked to her, tapped her on the shoulder and she went into the wall, getting hurt. but that was by accident.

Goku had hit chichi, but not in purpose. I think the first one was when Goku came back from Yarddrat- planet and he asked Chichi to allow Gohan to be trained for the androids. Goku just said with a smile: "Oh come one." And he hit Chichi's back but cause Goku didn't estimate his powers he hit accidently her through the wall, tree and the next stop was her head in the rock. ^_^

no Goku is too honorable to hit a girl he did'nt even want to fight Arale

no he hasnt not

yes wen he wanted to train gohan to destroy cell

In the manga, Goku was laughing about how ChiChi was overreacting, and he smacked her through the wall.

yes, when chi chi overeacted at gohan fighting the androids, he smacked her and she went flying though a tree.

he beat her with one hit in the last Budokai tournament back in Dragonball so yeah he has