On lines 33, 41, 122, etc., you have put two "==" (a test for equality), instead of just one equal sign, (for assignment).
Turn on your warnings on your compiler, and you'll be told all this and more.
Variables x and y are never used in survivalRule(), birthRule(), etc.
Life[][] is an array of char's, so don't print strings. Add a sleep(1) or more, between the display of generations, so you can see what's going on.
What it REALLY needs is a board display that doesn't scroll on the screen. You can do that using the header file <conio.h> with gotoxy(), in Turbo C, or use the Windows API and use Gotoxy(), along with <windows.h> header.