Respawn Entertainment's Vince Zampella tweets about multiplayer support in Respawn, saying their upcoming mech game will support six-on-six multiplayer games, saying limiting this to 12 players is best for game balance: "6v6 is max player count. Turned out to be the best balance with ai for us," then clarifying "that's humans only count. There are lots of ai, everyone can have a Titan in follow or guard mode too." He follows with some responses to the reaction this inspired, saying "we had it higher at points in testing, this felt best," and "a 6v6 game can be a crazy experience, very fun." Thanks Destructoid via Beyond Entertainment, where they note a post from a Respawn employee about this on NeoGAF, and here's part of that:

And FYI, for amount of stuff happening at once in a map you'll be hard pressed to find a game that keeps the action higher. I literally have to stop playing every few rounds because my heart just can't take it some times. Remember, you can get out of your Titan and let it roam on AI mode - meaning there can be 12 Pilots wallrunning around, 12 Titans stomping below, and dozens of AI doing their thing.

Oh, and I keep seeing people thinking we've got "bots" when we talk about AI. Thats not how they are. The AI in Titanfall are not replacements for human players. Our playercount is not 6v6 because of AI - AI play their own role in the game and are a different class of character in the game.