Putin has been Russia's leader since December 31, 1999, after Yeltsin's resignation. He was elected President in 2000 and 2004, and then in 2012 and 2016. The constitution did not allow him to be President for 3 consecutive terms, so between 2008 and 2012, he was Prime Minister, but he's widely believed to have essentially run the country in that period as well.
The question will resolve when Putin, for whatever reason, is no longer either President or Prime Minister of Russia, as indicated by credible media reports.