Actually most pundits tie the fact that there is a significant difference between who people polled say they are going to vote for and who they say they think will win to the reluctance of a significant number of voters to disclose they are voting for Trump because the media/pollsters have made it unacceptable.
The other poll question that pollster sometimes use to get people to disclose the truth is “Who do you think your neighbors are going to vote for?” Apparently people are more willing to out their neighbors than themselves....:-) Trump wins on polls that have asked that question, too.
The other thing in the past that has led voters to say they think the candidate they are not supporting is going to win is that the majority of the polls have indicated that. Well, we certainly know that is not the case in this election....:-)
Never!
And I was born a long time ago....