Well to be honest, telling a child they were a mistake because you, as a parent, are pissed about what your 14 year old said in an argument is emotional abuse, flat out. My parents would have never said something like that to me.
Sounds like a bad situation. If hitting was involved, it seems unlikely to me that the rest of it is fine. Also the OP said that he yells at her if she tells him she doesn't want to work, doesn't really sound like it's her choice. But it's true, there is limited information here.
Making a 14 year old have a job at the family restaurant is not abuse. I assumed he owns the restaurant though now I can't see where the post actually specifies that. Working from an early age helps to teach responsibility and not being lazy. But the total content of the post makes me feel that something bad is going on here.
Although it could be that the OP is a similar age and is friends with the girl (if it's not about the OP him/herself), and the girl is pissed about her dad and venting and making it sound worse than it is. Hard to say.