I heard 6 months supply on radio this morning. But, if Russia attacks on all fronts then Ukraine's reserves will run out faster.Ukraine has enough stashed weaponry to fight another year allegedly. Not sure if that included already agreed aid that's been stopped.
Cutting off US satellite intelligence would be devastating.
But don't underestimate Ukrainains. They repelled Russia when then only had anti tank weapons. They will fight to the death.
Most of Ukraine won't be lost.