The Ukraine is not taking Russian gas. They take fifteen percent of the gas for transportation across the Ukraine through their pipeline. You know, to operate the pumping stations to keep the gas flowing. You cut the flow by ten percent, they cut the offtake by fifteen percent. You cut the flow by fifty percent, they cut the offtake by fifteen percent.
Russia wants to increase the price to Europe and blame the Ukrainians, and is doing that now. Russia figures to boost the price of the oil to make up for the loss of natural gas going through the Ukraine. Russia previously renationalized the oil industry to make sure they got the increase in oil prices.
But what the Ukraine is doing is to cut off the supply of gas to the factories in the eastern, Russian speaking part of the Ukraine, which are owned by the Moscow types, instead of cutting off natural gas to the consumers in the Ukraine as a whole.
I just find it hard to believe that if you push gas into a pipeline it won't come out the other end simply from the insertion pressure.  Does it get stuck?
More or less, yes. It's called viscosity.
Big whorls have little whorls
  That feed on their velocity,
And little whorls have lesser whorls
  And so on to viscosity.

     -- Lewis F. Richardson