This isn't something that can be answered without knowing a lot more info. We aren't hugely concerned with how many players are left or where you are relative to the average stack; rather, we want to know how many blinds you have and how many your opponent has.
For the question you asked in your original post, you'll need to estimate the range of hands your opponent is opening with, the range of hands he is calling a shove with, and the equity you have when he calls. If you don't have PokerStove
, download it and spend some time toying around with it. From there, start saving the hand histories for the hands that you're wondering about, that way you have all the details necessary to do your calculations. Then, use a calculator, either in Excel, or one like the FPP Pro FE calc
. Plug in your data and it'll give you an idea of how often he has to fold to make your shove profitable.