The Ukrainians are 50 miles from Mariupol. That's still a long way but nothing Russian inside Ukraine is safe anymore.
They've been 50 miles from Mariupol for over a year now.
Ukraine is making progress, but at a rate that will not win them their territory back. To me it looks like Ukraine is conserving its reserves, which is the right thing to do, and waiting for more weapons from the west: Abrams tanks in September, F-16 in March, and the usual artillery shells etc. But Russia isn't just going to rest on its laurels and do nothing, they're also ramping up production of artillery shells, tanks, missiles, drones, etc.
Also, whether Ukrainian strategy is successful hinges on casualties. If Ukraine is exchanging people for territory, they'll run out of men before Russia runs out of land. They need to be at least 5-10 times as efficient at eliminating Russian soldiers and equipment than Russia is at doing the same to them, otherwise they'll lose the war of attrition.
I think a possible path to victory that Ukraine might have is if their slow and steady crawl causes Kremlin to implode internally.