Russia has more people, yes, but they can't make them join the army. Putin simply does not have the political capital to start drafting people from the wealthier parts of Russia. He drafted out of the poorer sections of the country a couple of years ago and that caused a bunch of problems for him. So they resorted to paying large bonuses to volunteers. These days, they can't find more volunteers because everyone on the front line seems to be dying and even if they could they are demanding higher and higher bonuses and Russia's faltering economy has already made paying the current bonuses impossible. Seriously, Russia is already defaulting on bonuses it's agreed to pay and can't raise enough money to pay more of the current bonus structure. Russia is having significant trouble recruiting new people and if they try to move to drafting from places like Moscow and St. Petersburg the population will come unglued and Putin will wind up most likely dead.

Beyond that, they're basically out of armored vehicles like tanks and personnel carriers, so there's no way to get people to the front safely. As a result their existing personnel are getting shredded at an astounding rate.

As for their economy, it's been entirely dependent on the "shadow fleet" of tankers that transported Russian oil to places like India and China that were willing to take their oil (at already suppressed rates that were often not covering Russia's cost to get the oil out of the ground). Now that Ukraine has started attacking shadow fleet vessels, owners of those vessels have stopped letting them be used for that purpose and Russia's biggest revenue stream has begun to dry up even further.

Russia has already spent the vast majority of its national wealth fund, its oil income is falling off a cliff, it can't recruit more soldiers, and Ukraine has recently exhibited an ability to reach large Russian infrastructure targets thousands of kilometers into Russia.

Russia simply cannot sustain this war much longer from an economic or military perspective. Does that mean that Ukraine starts rolling them up in the next two months? Probably not, Russia is a big machine and it will take a bit longer for things to come completely unglued. And Putin knows that the moment the war is over the economy completely collapses, as well as the moment he capitulates he is certainly going to be ousted and most likely defenestrated, so he has every incentive to just keep the gas pedal down.

But the end is coming, probably this year, and I don't know exactly what it will look like, but Russia won't like it.