More people talking about how Russia needs more soldiers...even if Russia had 600,000 soldiers dedicated to the invasion they would end up in the same situation as now.
The problem is their ROE. They have all of the disadvantages of fighting on home territory (protecting civilians) with none of the advantages. Having more soldiers would allow them to push a little further but their offensive would ultimately grind to a snails pace once more towns and cities needed garrisons and support.
My suggestion to the Russian command. Reopen up a front in western Ukraine. It was the original plan until someone (Putin) likely decided to interfere. It'll cost lives and will be more expensive to get to Kiev compared to the first time, but is the only logical answer to the current situation.
Once you get to Kiev, offer the Ukrainian army garrisoned there the option to fight outside the city like the US 5th army offered to the Nazis before the battle of Rome. If they refuse, and being Ukrainians I expect them to, start mass bombardment of army positions in the city. Treat Kiev the same way Ukrainians have been treating Donetsk for 8 years. Artillery, in particular thermobarics are much more effective in cities than empty fields.
Once everyone is dead or has fled Kiev, move to the next west Ukrainian city and repeat. Keep doing this and you'll find the Ukrainian army will leave ethnic Russian areas in the east of their own volition very quickly.
If Putin wants a geopolitical battle he can carry it on with Ukraine gone, he can pick the Baltics states or Poland. Anglos will whine muh war crimes, but seeing as they're already doing it already I don't see the difference. To that you can refer them American actions in Syria or Iraq. Better yet I would appoint a Jewish or black guy as commander and accuse the Americans of being racist or anti-semitic.