Does it count as a lost game (number of your finished games increases, but number of your won game doesn't) or is it not recorded in stats at all, like the game never happened?
Is it the same for people who got eliminated before the vote commenced ?

It's not counted to stats at all, it's only recorded as a completed ranked game.

I think those eliminated before voting happened are considered, well, eliminated. You can see that their "status" (in the player list, on bottom-right) doesn't change, while, for example, if a player from one team is eliminated and his team still wins the game, his status changes.

but if it's counted as a completed ranked game then it would be the same as a loss
while if it just shows it as a completed game, then it wouldn't.

ie, 250 completed games, 70/170 ranked games

So ... does anyone know for sure? Fizzer ?

There's another thread about it somewhere.