What would happen if funds to Ukraine were stopped completely ?

Presumably, the war would grind to a halt, as Russia would lack the numbers to advance, but Ukraine would lack the steel to break up Russia's positions. From there, Russia would go back to bombarding civilian targets with the limited artillery they can still supply, while Ukraine would launch artillery at Russian positions.

Ukraine's economy would further weaken over the course of the next several years. Power outages and foot shortages would grow progressively worse and investment in industry would have completely stalled out. Russia would slowly creep westward, and would at that point have to choose between annihilating the civilian populace or fighting a decades-long guerilla war against organized militias. In either case, we'd see civilian deaths totaling in the millions, and a refugee crisis which would make Syria's look like a joke.