There are two different ways a win can be achieved. The most direct way whch will instantly end the game is to destroy the large turret that protects your enemy's base. This is not as easy as it sounds as the turret is able to take punishment and also deals it out to your forces.
The other way the game can end is by taking and holding the various Hardpoints on the game map. Every second you control a Hardpoint will earn you points. If you can accumulate 100 points before your opponent you will win the match regardless if both bases are standing. This also isn't easy to do as Titans cannot be used to take or hold Hardpoints.
There is a time limit on matches so if neither you or your opponent has destroyed the others turret or accumulated the 100 points the winner will be determined by who has the most points when time has expired.