As far as conventional arms go: Russia has quite a few planes, tanks, and artillery; however, so long as the USA wills it, the Ukraine will have more anti-air missiles, more anti-tank munitions, and more long-range rockets.
In any long-range fight, being able to locate your enemy is key; the pentagons ability to identify the location of Russian positions appears to be unsurpassed. So long as they are passing this intel to the Ukraine, along with long-range weapons to act on it, any attempt at a Russian advance will be done without access to local command/supply posts.