My rabbit was abused in the past. Will he learn to trust someone else?

Yes, but you need to be especially patient and understanding. It takes time to build new associations with people and forget about the past. Be sure to give him a couple of different shelters to hide in, as rabbits cope with stress by hiding. Then, when the world is quiet, he's more likely to summon the courage to come out. Try sitting on the floor near him while you read a book. This will help him grow used to your presence. Offer him tasty treats such as dandelions or parsley, but don't force attention on him. When you handle him, sit on the floor and use a towel, so that you don't get scratched and he can't fall far if he wriggles.