Just putting some of the recent numbers into context.
The sources are below. Note that the relative population comparisons should be treated very cautiously. Many Russians and Ukranians are now abroad. Also many Ukrainian nationals are in occupied territories. It is hard to be sure of accurate numbers.
https://www.bbc.co.uk/news/world-europe-68397525
https://kyivindependent.com/general-...ps-in-ukraine/
https://mil.in.ua/en/news/general-st...-enemy-losses/
https://en.wikipedia.org/wiki/Demographics_of_Russia
https://en.wikipedia.org/wiki/Demographics_of_Ukraine