Survivor is a single elimination free-for-all game type. For this achievement you need to be the last person to die. That means that everyone has died except for you and so you have won the round by being the last person standing.
A simple way of doing this is to set the time limit to maximum and then sit in a corner away from the fighting with a shotgun. You will have to kill at least one person so be aware of how many people are left alive. I’d recommend getting a GPS device so you can find your enemy when there is only 1 left.
That or you could set up a match with a friend and just have them kill themselves at the start of the match.