I do not know what they will pay Ukraine every year (each year?). But I know that they always pay even if the Ukrainers steal the gas and/or block it.
Besides there are many other bad tricks what they do to their Russian cousins, not only blocking the access to Crimea and the 2 separatist republics of Ukraine people and their bombarding but also stopping electrical supply and recently the water supply. That's a real blackmailing, relying on their big friends who send their cruisers in surrounding waters, however, no longer enough money to support as they supported before.
The Ukraine is on the brink of bankruptcy, their population has dramatically declined.
But the dangerous Mr. Putin still has been very patient. Despite being claimed and accused that he will control Germany and the all EU? The gas has been flowing to Europe over 30 years (40?) and never has been a case of curbing the supply despite the permanent sanctions and other friendly actions against them.
And they "have to" supply the gas for EU through Ukraine? Now, after what they invested such huge projects under such huge adversary? Any such similar case in other friendly and so not so friendly countries?