I just dodged from a champ select because one of the players on my team had not connected yet. Does the game even start if one of the players hasnt connected yet, or do I really have to lose ELO over that?

You lose Elo for dodging, or a 100% loss.

You have a chance of losing Elo for playing the game, or a ~75% loss.

Do the math. You lose more Elo by dodging than by actually playing. You also get a chance to report them after the game instead of throwing them back into the queue with other people.

Thx, i know that I lose ELO for dodging. The question was "Does the game even start if one of the players hasn't connected yet[?]"

I wan't to know if next time I see that one of the people on my team has that "stupid little Triangle with the Lightning Bolt in it" Icon over them does the game abort, or does Riot really let a game start 4v5?

I just got in a game where one of our members was clearly not there. The game picked a champ for them then proceeded to start the game instead of throwing us back into queue. All nine players reported her, but that wasn't a very fun loss since we knew it from the start.

If a player hasn't connected at all, the game won't start, but in the case of an AFK, it probably will.