Does Gaijin even do anything about reported team killers?

Had a guy push me off the bridge into the water for no reason… I watched the replay and followed him and he did it again a few minutes later to another player. If you report them does Gaijin even do anything about it?

Yes

Allegedly yes in practice very unlikely. Just imagine the sheer volume of reports that have to be investigated, not totally sure how the company proceeds with a report it may be that a number of complaints in a specified time frame about a player instigates a further enhanced investigation.
Doubtful that the process is fully automated too much room for mistakes.
Unless a large percentage of your team complained or the player is a serial TKer chances are nothing will be done and it takes ages anyway.

only if the guy teamkilled was a mod

I am pretty sure it cant be full automated. Having MORE complaints on the same guy will probably increase the odds of he being checked.

SO…complaining will help and players do get banned. (Some came to forum complaining about it)

Of course it is faster to ban players that use cheats (can be auto checked) or chat profanity (easy to check…even some auto is possible). TKs are also checked, but it seems to take longer…