The main variable of these conflict rely on two metrics :
1 of all- number of shells you can put on your enemy from each side
2 - logistics : how you can feed the beast ? And where are the kitchens.
20000 shells/day for russians, 6000 shells for ukrainians
If all the logistics come from the US for the Ukrainians then this is A 15000 km long way and ... most of it by plane then trucks Kithchens are mainly in US. But this will change during next winter.
For the russians logistics is by train then trucks and kitchens are mainly in the other side of the border.
If you look at only the logistic we can already say where Putin want to stop the war : at the Ukrainian border because trains in Russia are not compatible with eastern railroads.