It depends on the ingredients in the filling. If they are ingredients that will shrink during baking, you might get a gap. If you have ingredients that the moisture will bake out of, then you will probably get a rip or bleed.
Usually though, if your filling has a thin top layer of the filling juice or gravy on it before you put the top crust on, and you press the crust down a bit while you roll it onto the top, you should be ok. But sometimes there are gaps because an air bubble is in the filling somewhere and when it bakes, it rises to the top and creates the gap. Just be sure you don't have any air bubbles in your filling when putting it in the crust.