The greatest benefit from including silica gel in your camera bag is to keep the inside of the bag dryer than the outside air when stored at room temperatures that tend to be fairly moist for long periods of time.

If you bring your cameras in from a cold environment, particularly sub-freezing temperatures and then bag them in a warm, moist environment nothing is going to prevent problems from condensation. If you bag the camera gear while still in the cold environment and then take the bag inside and allow it to sit unopened for enough time to warm to room temperature the additional insurance of the silica gel can't hurt. This is based on the assumption your bag is fairly air tight and doesn't have a lot of voids with air pockets when your gear is stowed. Otherwise you may want to place the camera gear in an air tight plastic bag until it has warmed up.