Size of the club is kind of part of success in TWs but not in a hugely direct way. Certainly not as important as it is in clashes.
Turf Wars are about volume of coins won.
Bellagio bet is 2.5 million. Depending on coin apparel bonuses this is going to be interpreted by the game as anywhere between a 4.5 million win to 5.2 million win.
So really the key to Turf wars is having more people that play Bellagio than your team. It's impossible to play enough to beat a club if they have even one Bellagio player. I've been in two clubs that don't really care about Turf Wars and as just a solo Bellagio player i can burn 4 passes and usually win 3-4 of them so that's 15-20 million. Just me.
One Bellagio player can win 2/3 of the Turf wars out there by himself. More if he/she just wants to burn the credits on passes.
If you want to win TWs then be strategic. Build up a coin roll and start playing Bellagio.