Well, we're close to finding out one way or the other.
If I had to make a prediction: I think Harris will win and the map will look pretty similar to 2020. I think that, much like then, the dominating factor in the race is that Trump is extremely polarizing and unpopular, and I think basically nothing he's done since then has changed anyone's opinion on him- and the things that maybe have changed people's minds, like J6 or his criminal cases or his general seeming like he's losing his mind, have been changing people's views on him for the worse. I similarly think Harris is, much like Biden 4 years ago, kinda unpopular but not nearly as polarizing or unpopular as Trump. I certainly think some things are working against the Democrats now that weren't 4 years ago (the inflation of the post-COVID economy, mainly) but there's also things working in their favor (the Republicans' deeply unpopular stances on abortion). Gaza honestly probably won't matter much- most Americans just don't care all that much about it, and for those of us that it would matter, either they're (rightfully) concluding that Harris is bad for Gaza but Trump would likely be worse, or they were never going to vote for Harris (or any major party candidate) in the first place.
As to the theories of the polls, I don't think they're horribly off, but I agree with the theory of "the pollsters are afraid of missing on Trump again and overcorrected and now they're too high on him and they're herding to a tie race because they think that's the result they should get and they're afraid of taking a bold stance and disagreeing." If I had to make a guess as to what exactly the map will look like, I'd go with the same as Biden's, minus Arizona, but plus North Carolina (purely because I think the Republicans' horrible governor candidate will drag them down a bit across the board, just enough for Harris to win there), but a bunch of the states could really go either way.
As to Congress, if I had to bet, it would be on the Democrats narrowly winning the House while the Republicans narrowly win the Senate (thanks in large part to the map heavily favoring them) with either 51 or 52 seats- I think they'll very likely win Montana (and hold Texas and Florida) but Ohio's a toss-up, and I doubt they'll get anything beyond that because of their continued propensity for nominating really flawed and unpopular candidates like Kari Lake in Arizona.