Lets start off with some clarification. "Total Control" is the name of the game type which can only be played in Big Team Battle in which 3 areas/zones labeled A, B, and C spawns somewhere on the map and your team has to control all 3 zones to gain 1 point (for a total of 3 to win) and then they spawn again somewhere else. The "Total Control" game mode can be easily be confused for "Strongholds" (A 4v4 game type) which your team has to control 2 of the 3 zones to start accumulating points for a total of 200 to win.
Zones A, B, and C start off neutral and your team has to capture all 3 areas to gain a point, and you must assist in capturing all 3 zones to gain this achievement. In by assisting you must be inside the zone and help capture and it does not matter how long or if you were inside when your team got the zone as long as you helped. If the enemy team takes back a point you probably have to help take it back so it counts again. I don't think you need to do this in one life as when I was helping capture the last zone I died but my team got the capture and the score and I got the achievement afterwards.
A tip I can give is stick close to your team when they start pushing for the objectives so you can be there to assist in the capture of the point. You don’t want your team getting the zone when you didn’t help capture because remember you need to assist in capturing A, B, and C. But it’s most likely that it will happen, but again it’s gonna be a back and forth game most of the time. The zones that you didn’t help get but the enemy got you can help get it back so you get the assist for that zone.
If your lucky and have a good team you may be able to snowball the objectives via getting zone A to B to C or vise versa, and it will definitely help if some people stayed and defended (not you though) the already captured zones just in case.
So apparently the achievement might be a bit buggy. You may be able to get it if you helped assist all zones at some point but it not leading to a total control for the score.
Correct me if I got some things wrong, hope this helped or clarified things for you guys!