Every 'Blue Wave' poll I look at seems to oversample some combo of Dems, Indies, women, and Millennials.
In the mid-terms, it's Republicans, men, and over-55 that tend to be the majority of turnout. Dems, women and 35-45 come in second, and the under-35 (Millennials right now) and Indies are a distant third, usually 50% or less turnout rate than older GOP men.
I think things are better for the GOP than the media claims, and most of the polls are liberal psyops.