Well, i'm not trying to be rude or anything. But if someone says ' I don't know' It simply means no. They are only saying that they dont know because they either dont want to hurt you, or they cant think of a nice way of saying no. It's obvious, because if he does like you, he would just say it.
If he doesnt know , then will who will know, you cant tell what he is thinking so its not worth waiting to for a respond , so just give it a little time until he "thinks" about it and well, whatever happens, happens ;)
Its hard to say if he does or not. Ifs its been over a month then either he's stalling or don't know what to say to you, in my opinion I would go to him and see whats up, and if he still doesn't have a answer then he's not worth it, time don't wait for no one and you don't have time to loose, but if he's worth the wait to you then its up to you, can't no one tell you what to do, you'll know when its the right time to say something