The only answer can be "yes" and "no".
Chinese miners representing over 80% of bitcoin network hash rate have reconfirmed their support for SegWit2x
This is an interesting one because the 14 pools they list vary from Bitmain (Antpool) with ~17% of the total network hashrate, to people like 1Hash with <1%.
Shows 4 pools (Antpool, BTC.TOP, F2Pool, BTC.com) have more than 50% of the hashrate. If you include 3 more (BTCC, Bixin, BW) you're at ~70%. AFAICT none of these will let the users decide how they vote*, after these pools is Slush (~4.8% over last few days) which allows miners to choose what to "signal" via the coinbase transaction.
As Pieter Wuille points out, they can agree on what software to run, but they don't have the authority to change the protocols, there is nobody to "allow" or "disallow" it, they do as they like, the markets will decide if their coin is worth buying.
*F2Pool is interesting, as they did poll users to see whether they should signal SegWit, after the vote they started signalling, but this is superseded by SegWit2x.