They have 70 million plus male potential soldiers. Through the first year plus, the Russians were concerned with the depletion of their arms. They have gone into a war economy where they have increased arms prduction. They have leading edge arms production capability. The war has resulted in Russia being more prepared for war, now, than they were before the war.
You take a nation with a military and you kill large numbers of men and destroy large amounts of equipment and you are weakening that nation.
Russia might have a large number of people. The median age is over 40. That is not a nation that wants to lose a lot of young men. They are already dying and losing those young men is just killing them faster.
This war is bleeding russia white. Every day that it continues, Russia is more fucked.
Putin is being a fool, in passing up a chance to cut his losses.
Thus Trump has plenty of leverage. Every day Russia is dying by inches.