The influence that a happy (60%+) faction gives depends on its support. A faction with 100% support will generate the maximum amount of influence. A faction with less generates a percentage of the max equal to its support. Support is defined as the percentage of pops supporting a faction.
In this case, the Free Citizen Centre is generating 54% of the max influence, while the Xeno Protection Council is generating 38%. The fact that they're even happier doesn't change anything- all that matters is that it's at least 60%.
The initial max influence from factions is 2, but this can be increased by various methods, such as:
- Society Technologies, such as The Living State chain
- Egalitarian Ethics
- Civics, such as Parliamentary State