Does Hitler's bunker still exist

A few bit and pieces may survive but none of them is open to the public.

Yes, there are walking tour in Berlin that can take you to the bunker site. It is located now in the backyard of an apartment complex. You can stand on top of it and even see the entrance to it but it is completely sealed off and no one is allowed inside. If you are ever in Berlin, good luck finding it on your own considering there are no signs or anything to lead you to it. I doubt the Germans want it as a tourist attraction considering the outcome, which I don't blame them.