I asked that question months ago and got an answer but I don't remember the details for sure. I'm sure it's still on the forum. My memory is that they still eat, but they themselves won't starve... or that if they get pegged for starvation, the random wheel of starvation gets spun again, and that time will stop if it hits someone with survival again. I'm guessing with flawed memory though.
Kristoffer there says that terrain survival gives a 50% chance of avoiding the starvation. My own experiments resulted in survivalist troops still starving, so they are definitively not immune to starvation.