Well, JYP did have an entire survival show about eliminating members if he felt they didn't fit or weren't ready to debut, but some of us think he knew since the start all members would be there and just wanted to create drama + maybe free Lee know and Felix from filming schedules so they could get more hours to train, this doesn't mean the guys themselves knew though.
Jyp himself said they trusted Bang Chan because he had trained for so long and because of his skills, at some point he was the only male trainee to not get cut out which means they saw a lot of potential there, and some skz members said Chan's team would always place first during monthly evaluations.
There's some theories that Chan did not pick Lee know and that it was the company's decision because Lee know joined the company like a month before the filming for the survival show started, buuut he did pass all of the basic dances in 2 weeks, the 2nd fastest trainee did it after 2 or 3 months, so maybe Chan did pick Lee know after seeing this. Then there's theories that Chan wanted other trainees to be in the group (Cravity's Allen and now soloist Yao chen) but they weren't in the survival.
During 2 kids room I.N did mention how thankful he was that Chan wanted him to be on the team or otherwise he would have been put with younger trainees and wouldn't have been the youngest anymore, so overall i do think Chan had the possibility to form the team.