You will not lose the Survival update simply by going offline. I’m not sure if you can play survival mode offline, because you would be playing with bots, and I don’t think they have special infected bots on survival.
As @sweetteaindahouse said, just go try it. This isn’t really the place to ask this question.
@xboxfan No problem. Try making your question look nicer next time by simplifying the topic question, adding more detail to the detail part of the question, and using correct punctuation and grammar. If an “i” is by itself in a sentence, you capitalize it.
@xboxfan Fluther is a very tight community, and we lurve our people to us correct grammar and spelling. We reward that with lurve by giving Great Answers and Great Questions.