Does creating games for the platform help the platform succeed? Like if I create tons of games for 1 platform does it influence it? If not then what controls a platform's marketshare?
It certainly does for your own console once you finally make it. Every time I made a game for my console the sales of it rocketed.
As far as other consoles I wouldn't say so. PC naturally dips and then starts to get better, it could have been coincidental timing. The way the game is designed is such that you're supposed to take note of the market share of each console and work around it, rather than control it.