I do like you..just confirms that yes you like someone. I really like you...really is a degree, it means you don't just like the person, you like them a lot.,
你喜欢我吗?, 对/是,我很喜欢你。Do you like me, yes I do like you.
你喜欢我吗?对/是, 我非常喜欢你/我真的喜欢你 Do you like me? Yes, I really like you.