Have you got a brother? Yes, I have. (and that's enough)
Do you have a brother? Yes, I do. (NOT Yes, I have)
Have you a brother? Yes, I have. (this version is possible, but not commonly used in the modern language)
Remember:
* in short answers to Yes/No questions you normally use the operator only, e.g.
Does he like us? No, he DOESN'T.
Have you ever flown in a baloon? Yes, I HAVE.
Are you coming next week? Yes, I AM.
Did they see you at the concert? No, they DIDN'T.
Were you watching anything then? Yes, I WAS.