Brian Wang puts the situation into perspective.
There are estimates that Russia has lost 40,000 soldiers (killed or wounded) out of 190,000 after the first three weeks of the Russia-Ukraine war. Russia has 900,000 in the military but this includes Navy and Air Force. Russia has about 250,000-300,000 in the Army. Russia has 2 million in reserve but those are mostly x-conscripts and 14 million men of military age (18-30).
Independent UK and many other sources cite a senior NATO official estimate of up to 40000 Russian Casualties.
NATO and US estimates of 7000 to 15000 Russian war dead. (via AP).
According to Oryx, as of March 23, 2022, Russia has lost somewhere in the region of 279 tanks, of which 116 have been destroyed, 4 damaged, 41 abandoned. Some 118 have been captured. (via interesting engineering and other sources.
Putting more untrained people into this conflict will just get most of them killed. One of the Russian problems is the poor training of its military. The other aspect is that the death and wounded rates could go up if Russia commits to major urban warfare. If the supply line situation is as bad as some reports indicate then the 70,000 soldiers in the north could run out of ammo and food and collapse. This would mean a lot killed, wounded and captured.
Russia started the war with 1200 Tanks committed to the conflict. Russia had about 2800 active tanks. They had about 10,000 Soviet-era tanks in storage. Those tanks in storage were not modernized and are even more crappy that what Russia has been losing. Russia has lost 270-500 tanks already. All of Russia’s tanks are vulnerable to Javelin missiles. There are 17000 Javelin missiles in the Ukrainian army now.
Russia has lost 100 planes and Russian pilots are flying very defensively. They are trying to avoid getting shotdown instead of focusing on military objectives.
Putin/Russia should already cut a peace deal and withdraw. Losing the northern Army (70,000) would be an even greater catastrophe. Going into Kyiv or any other major city in urban combat would also ratchet up the losses.
It took Russia twenty years to make 2800 modern tanks.
The current pace of losses cannot be sustained for more than two more months. Four more weeks of losses at this pace is devastating as half of the soldiers they went in with would be injured or dead. Russia is already digging into defensive positions. Unless there is a significant improvement in strategy and tactics there is no way that even with 50,000 or 100,000 new conscripts or other force replacements would a second offensive be effective in taking Kyiv or other major Ukrainian cities.
It is even difficult to see how Putin/Russia could sustain a campaign with annual losses like the first month of this war.