Its trade volume is usually 8x to 10x that of Bitstamp. If that translates into liquidity too, then Huobi will have a much larger effect on Bitstamp than the other way around.
Namely, when an arbitrager buys an amount of BTC on Huobi and sells the same amount on Bitstamp, the drop at the Bitstamp is usually much bigger than the rise at Huobi. So the effect of arbitrage is to pull Bitstamp closer to Huobi, rather than the other way around.