……but wasn’t a hit and got mediocre ratings, but just enough to keep it on the air. Do you think the Jeffersons would have been cancelled earlier? I do. The show needed Florence badly.

Yes. George and Florence's relationship made the show work. The original plan for Checkin In was to have the building manager be like George Jefferson and put down Florence for laughs. But the producers found it taking on a racial component. That is a reason the show flopped. Both shows were missing this dynamic couple.

It depends on who else was there. They replaced Florence with Roseanna Christiansen as Carmen, but the show is the first credit for her that lists on IMDB. My guess is that if Checking In was successful, they'd spin housekeepers in and out till they found a good foil for George.

No it would not have been cancelled because during the beginning of season 8, Florence was not seen until the 7th episode the show was still in the top ten during October of 1981 and first half of November.