The difficulty in Survival keeps scaling up for each wave. At wave 100, the difficulty is 1000. So, it gets pretty tough. What difficulty are you able to get through in regular games?
When you can beat Survival is going to depend on how you play, which map you use, and maybe luck, to a certain extent. A lot of people bounce ground units back and forth by removing and adding towers, so the enemies keep going past the same towers until they get worn down. If you do that, and use a lot of teleports, you might be able to beat Survival sooner. FWIW, I don't do the bouncing thing and was able to beat Survival when my upgrade levels were around the low to mid 30's.