Even if you could get the information (which you can't), it would not be very meaningful to an outsider anyway.

The outsider tends to think that if an aircraft has 100 seats, then when 50 "tickets have been sold" then there are 50 tickets left to sell. But it doesn't work like that. They are not tins of baked beans on a supermarket shelf.

Similarly, an outsider might freak out if they were to discover that six months before the flight, the airline was holding reservations from (say) 170 passengers for that 100-seat aircraft. But that would be no indication that anything like 100 (let alone 170) passengers would actually seek to check-in for that flight on the day of travel.