How likely is a split? For now, it’s perhaps too early to say for sure. But with that in mind, we do have some indications given the mechanics of how Segwit2x has been coded. This is because: Segwit2x uses BIP 9 activation. This means that the rule change is governed by the percentage of miners running the new code. Miners mostly support Segwit2x. 1Hash, Bitfury, Bitmain, Bixin, BTC.com, BTCC, BTC.Top and ViaBTC all signed the original agreement, reached in May. On paper, the plan boasts roughly 80% of the network's miners as signatories, a group some believe is big enough to switch the majority the network over to the Segwit2x chain, and quickly (for fear of being left on an unprofitable software).

https://www.coindesk.com/understanding-segwit2x-bitcoins-next-fork-might-different/