Ukraine Crisis
The issue isn't actually one of overall military power or even Russia's or Ukraine's ability to attack/defend, it's a matter of home support and logistics:
The Ukrainian forces are far more motivated than the Russian forces, and are working with modern equipment. While you said the simple addition of modern technology won't sway the war, there is significance in the reliability and longevity of the weapons of each side, if the soviet-era weapons Russia is using fail due to poor upkeep or simple age, then the technology supplied will have, in part, swayed the war.
Furthermore, it is in the United State's interest to continue to supply Ukraine, and they can afford it, even with the growing dominance of China in an economic and geopolitical sphere; the USA spends an absurd amount on the military, and could afford to continue supplying Ukraine longer than Russia can afford to supply their war effort.
In conclusion, the supply of arms to Ukraine will easily continue, and the will of the Ukrainian armies will outlast that of the Russian armies; there is little chance that Russia will end this war gaining anything.