The survival mode in Call of Duty Modern Warfare 3 is not designed so that you can survive indefinably Eventually you are going to get swarmed and there will be nothing you can do. However, this guide will help you prolong your survival on most maps.
The basic jest of it is to make sure that you do not get cornered. That is that the enemies are only ever coming from preferably one direction, although most of the times two or three directions is manageable. To do that you will have to constantly check your mini map for the location of the enemies. Always make sure that you have an escape route should you get overwhelmed. Always clear one direction of travel, usually it is easiest to clear the one with the least enemies.
I advice against the use of equipment and air support because all of the equipment and air support never pays back for itself. That said, predator missiles are very useful when taking out Juggernauts. Also you will want to purchase body armor because that will let you mow down large quantities of enemies in the early stages whilst tanking the damage from their weapons.
below is a full list of all the maps on survival mode. I will update these as I produce them and upload them to YouTube.
Survival Guide on Village: