But the chinese exchanges had no trading fee for a long time(not sure if it is true today), how they managed to survive? Can't imagine withdraw and deposit fees alone making an exchange viable.
The fiat withdraw fees of Chinese exchange huobi/okcoin/btcchina are around 0.4-0.5%. If you trade in bitstamp, let's say to buy bitcoins and withdraw btc. You need to deposit fiat first, Bistamp charge you 0.1% deposit fee, assuming you are in highest trading fee discount class 0.2%, withdraw bitcoin from Bitstamp is free. For the person selling bitcoin to you in Bistamp, assuming that person is also in highest trading fee discount class 0.2%. So Bitstamp charges 0.1%(fiat deposit fee) + 0.2%(your trading fee) + 0.2%(trade fee of the person) = 0.5% for a pair of trade made by you and the person selling you bitcoin.
Apparently, Chinese exchange earns almost the same as the Bitstamp earns from trade. Also, Chinese labor is much cheaper than English labor!