Yes they will but they will not be visible immediately. If you own x amount of bitcoin in a wallet over which you have control of private keys then after the dork has been resolved you will have equal amount of the forked altcoin in that wallet. But to claim that amount you have do something yourself. Like for bitcoin cash claiming Electrum released the Electron Cash wallet and there is a method to claim BCH using that. Several other exchanges and casino bankroll investment sites like crypto-games asked users to put in BCH wallet address to claim their BCH if they had invested any BTC in their bankroll.