If there is an election, the Tories will win and the UK will leave the EU. If there is a second referendum, the remainers will win and the UK will stay in the EU.
If I know this then so does the "rebel alliance." Therefore, I am not expecting an election any time soon; not in October, not in November, not even this year. What will happen is that the "rebel alliance" will refuse to allow Johnson to go to the country until there has been a second referendum, and if Johnson and the government resigns then the rebels will form a coalition government with a workable majority as long as the only business they conduct is to revoke Brexit.
After they achieve this aim (which is what they are really after no matter what they say in public to the contrary) they will allow an election to take place and Boris Johnson's Tories will win a landslide victory the likes of which the UK has never seen, not even during the dark reign of Margaret Thatcher.