Can I feed a kitten breast milk?!?

We just rescued a kitten, he’s obviously not weaned and too young to be away from mom but she abandoned him and wouldn’t take him back, just tried to hurt him. So we took him. He won’t drink any water and hasn’t all day or eaten and all the stores are closed. Is it okay if I pump and give him some breast milk until I can get proper kitten milk from the vet tomorrow? I also don’t drink dairy so I only have soy milk. I know cats shouldn’t have dairy anyways but he needs to at least stay hydrated. Help please!!!