I think they know. In 2016, I think they believed their polls and were surprised by Trump's win. This time around, I think they know the polls are wrong, but have tried to use them and the story they tell to manipulate the election. Now that the day is almost here and it seems their efforts have mostly failed, they might drop the pretense. Or, if the election is close and the result contested, they'll double down and use the false polling data to bolster an election fraud story in favor of Biden's claim.