does anyone knows if bittrex will give the gold to btc holders?
There are already quite a few threads containing this question.
You can never be sure an online wallet or exchange is handing out the BTG to its customer.
You are not in control of the private keys (the actual coins). You are only registered on their website. And they allow you to "send/recieve" btc's.
If you want to be 100% sure, then you should send your coins to an address you are in control of.
Its not just better because of a fork. Security wise its definetly better than trusting a third party.
