Stepanov, a former employee of the Russian anti-doping agency RUSADA, helped expose massive doping problems in Russia in 2014 with his athlete wife Yulia Stepanova and the pair have since fled the country and live in hiding in North America.
Their evidence triggered a World Anti-Doping Agency (WADA) investigation that alleged the Russian government was complicit in an elaborate scheme of institutional doping.
"I have met a couple of months ago with Yulia Stepanova and Vitaly Stepanov. We have exchanged our positions and they were very good and friendly discussions," Bach told reporters.
"This resulted in the fact that the IOC has since then supported Vitaly Stepanov."
Bach did not provide any details on the kind of support the IOC was offering the pair.
"We are benefiting from his advice on anti-doping matters with regard to Russia and are supporting Yulia Stepanova and hope she can find a new National Olympic Committee which may allow her to qualify for the next Olympics," he said.
Stepanova cannot return to Russia, let alone compete for the country, for fear of her life.
The IOC refused to allow the middle-distance runner to compete at the Rio de Janeiro Olympics as an independent athlete, citing an older doping sanction in a decision that was criticised at the time.
Bach had rejected claims of a lack of support for Stepanova at the time of the Rio Games, saying: "We are not responsible for dangers to which Ms. Stepanova may be exposed."
Moscow consistently denied state involvement and the Stepanovs were denounced as traitors.
But on Tuesday the IOC banned Russia as a team from the Pyeongchang winter Olympics over the nation's doping scheme at the 2014 winter Games, revealed by another Russian whistleblower, Grigory Rodchenkov.
(Reporting by Karolos Grohmann, editing by Ed Osmond)
