Except in the real world Russian domestic industry has been developing at the fastest rate since the fall of USSR, and Russian economy is doing far better than any western economy right now. Russia also managed to redirect trade away from the west and towards the Global South where most economic development is actually happening now.

On the broader scale the war is between G7 and BRICS, and the US and China do indeed act as a backstop for both. Given that, it should be pretty clear why Russia will prevail in this war. Should Russia fail and become destabilized, that would be a huge disaster for China because Russia would become their Ukraine. NATO would be able to start building up forces on China's western flank, and to cut them off from access to food, energy, and resources they get from Russia. This is obviously not going to be acceptable to China. So, if Russia ever finds itself in trouble economically, China will necessarily step in.

On the other hand, Europe is backed by the US where economic woes are going from bad to worse, and hence why the US is increasingly distancing itself from the war handing over the burden to the Europeans.