Un Votes

[mazzz]

how is it choosen how many votes each civs gets? how can i increase my votes?

 

[QiZhe]

Population. There might be other factors, but I believe population is the main one.

One thing I did was start to invade a Civ that voted against me. Doesn't necessarily get you votes, depending if you occupy or raze, but it makes the other side lose votes.