BTG's price is not determined by bitcoin. Its determined by demand and supply. However the price of bitcoin influences other alts. Bitcoin is not responsible for alts to crash. If people try to dump bitcoin, they would also have to dump alts, so that those who try to influence the markets succeed in what they are doing. BTG is not a big altcoin, yet. Its just a third wheel type of crypto. People were forced to trade with it, in the beginning and now they just don't care.