Right—I was only writing about the character form. 食べる is used to mean to eat, but as far as raw characters are concerned, Japanese doesn’t use 吃 but rather 喫, the non-simplified form.
Apparently there is a use for 吃 in Japanese, 吃 is a sound used to represent a tile being discarded in a game, in compounds such as 吃驚, to be surprised. I think this compound is also used in Mandarin with the same meaning. Quick check of my Chinese dictionary indicates yes, they are a shared character compound / meaning.
Edit: fixing up my Japanese