USA aid is very important to Ukraine, but even without it they would continue fighting. Ukraine has been without USA material aid for months already in the past, when the republican party was blocking it. And as it turned out, Ukraine sustained higher casualties and had less offensive power than with USA aid, but they were never close to folding.
Ukrainians + their supporting neighbours are very motivated to not be occupied by Russia, so they’re not going to just give up if Putin’s stooges come to power in the USA.