Remember the national poll that the Sunday before the 2020 election said Biden was ahead of Trump in Wisconsin by 19 points? Biden ended up stealing it by a half point.
It shows up in the numbers versus Obama's record 2008 turnouts in Wisconsin.
This was in conjunction with all the other cheating going on - the illegal absentee voting, the drop boxes, the nursing homes, the Green Bay election offices, the Madison vote harvesting operation...
Even with mail-in / drop box shenanigans, the trumpeting of those obviously bogus polls is enough to have turned the election. Only a tiny, very small fraction of voters would be affected, but that’s literally all it took. There are enough “soft” GOP voters who would have seen all of that wall to wall coverage of that poll and thought “well, this is a lost cause anyway” and just decided not to bother.