It’s true, if you look at the map, it would appear that Ukraine is winning because it’s recapturing its territory. However, this is partially the result of a strategy Russia has now abandoned. Russia initially believed that it could win the war within several days, and as a result put little effort into logistics or preparing its reserves.
Russia has learned from its mistakes. Its armed forces are abandoning their initial goal of seizing Ukraine’s capital, instead focusing their efforts on the south-eastern part of Ukraine. Furthermore, instead of rushing into battle, Russian forces now rely on heavy artillery to bombard Ukrainian positions for as long as needed before advancing to capture destroyed towns and villages. Thus, their casualty rates have decreased dramatically, while Ukrainian losses have increased.
Moreover, the Ukrainian army has already mobilized all of its reserves and is currently at maximum strength. Meanwhile Russia has been bloodied but retains the majority of its massive army. Russia is able to replenish their losses, whereas Ukraine cannot. This is why aid to Ukraine is a matter of urgency, before Russia can regroup and bring in more troops.