At last count Mt. Gox still holds approximately 141,600 bitcoin and 142,800 bitcoin cash.
When all this BTC pours into the market, the price will fall.
Nah, it's just < 1% of the total mined bitcoins so it will just barely affect the price when that happens or nothing at all. Besides market now too hype that even 1% of sell order won't affect much, people from the other side will just buy it.