BCH started raising with BTC this month but sustained its value and growth even though BTC is down. BCH may not have this much growth (62%) in future but can withstand where it is in value for some time I guess.
No, it cannot withstand this amazing growth and sooner or later the price will go down hard. The coin is design just for pump-and-dump and I don't believed that it can replace bitcoin overtime.
What's best right now it just ride the wave and exit when the price is slowly declining because I think that it will be dump in the next coming days. Just observed how they are being pump, more than 70% which is very bubbly for me. Don't be over confident that it will be sustainable so that you will not be disappointed with it crash.