After the birth of the fork of bitcoin, both currencies continue to exist. The price of ordinary bitcoin, despite the emergence of a new currency associated with it, has not changed. Users seeking to obtain a new currency, are beginning to actively search the Internet exchange, which has a certain amount of bitcoin cash. If you carefully study the behavior of the exchange rate of both currencies, you can see a certain relationship between them. But most likely it will not last long, and once the usual bitcoin once again will rise significantly in price, its fork is unlikely to be able to follow it.