What happens if giveaway owner is suspended?

Nothing.

his suspension would be extended since he can not gift the winner in time :P

Depends if they want to come back to the website or not, if they don't they probably won't gift you at all,

i believe the difference between banned and suspended depends on when it happened, not the length... i peeked at raiden answering tickets and its possible for a suspension to be permanent. i think it says banned if it was before cg changed the system, so there is no info on the site about the reason why someone is banned (mods have their ways of finding out though). maybe im wrong though, these are just my assumptions from limited information