Russian losses are certainly high. At the end of last month, Nato estimated that up to 40,000 soldiers had been killed, wounded, captured or missing in action. This number is expected to have only increased in April as the Ukrainians managed to push the Russians out of various cities, including Kyiv and Kharkiv.
Article source: https://www.huffingtonpost.co.uk/entry/russian-invasion-morale-ukraine-putin_uk_624eb0e9e4b007d3845f94b7