I was kick out a group, but I'm in the group giveaway.

did you synced the SG profile with your steam profile?

Most groups will reraffle it.

Or, you can be a good guy and leave the giveaway instead of trying to steal something that's obviously not meant for you.

you should leave it

Leave it. They won't like it if you win, and they certainly won't actually give it to you.

Stay I would say and hope they'll give it. If not, you can get back at them for kicking with giving negative feedback. But that's only the small chance in case you win.