Update on the number of captured: “At a meeting in St. Petersburg on Wednesday, Putin told the heads of several international news agencies that there are 1,348 Russian troops and officers in captivity in Ukraine compared to the 6,465 Ukrainians in Russian detention.” See: Putin makes rare claim on Ukraine war casualties (msn.com)
Now, I find these figures to be entirely believable. The Russian Defense Ministry claimed as of 30 June 2022 to be holding 6,000 Ukrainians soldiers in captivity. This was partly confirmed in July 2022 when the Ukrainian missing person commissioner stated on TV that more than 7,000 people were missing, including soldiers, National Guardsmen, border guards and intelligence officers. Ukrainian President Zelenskyy stated on 19 September that the Russians held more prisoners than Ukraine did (see: The Battle for Kyiv, page 185). There were maybe 2,439 that surrendered at Mariupol in late May 2022. There have been other people captured in the two years since then. The prisoner exchanges have traded at least 2,800 Russians soldiers and civilians for 3,001 Ukrainians soldiers and 145 civilians. Plus there were some Ukrainians who died while captivity. Anyhow, it all seems to add up, although it could be on the high side, and the figure of 6,465 probably includes some civilians.
On the other hand, his assertion that he has lost in combat only one Russian for five Ukrainians is absurd. It is as absurd as some of the bizarrely lopsided casualties claims that Ukraine is exchanging casualties at a 3-to-1 to 5-to-1 ratio in their favor.