Did you beat the original game? If so, you should at least have access to the hospital survival level. If you got the DLC, you need to play and beat the 2nd and 3rd maps before you can see those.
Also, I assume you have logged into xbox live and did the mandatory 1.5 GB re-download that permanently changes the game from Trenched to Iron Brigade. Without that update, you have no access to survival mode.