Fauci, like many of us, got things wrong at some points. For example, we all underestimated the likely size of the pandemic because we were basing our guesses on the MERS and SARS-CoV1 mini-pandemics of earlier decades with similar viruses. Those "only" killed a few hundred people and were self-limited and not very infectious.
Fauci's main claim to fame is as a basic immunologist making important discoveries and having steered HIV research for decades nationally. His main positive role is emphasizing to members of the administration, and particularly the President, that this was a serious problem, public health measures were necessary (closing crowded public venues, masking, distancing outdoors) and that holy hell was breaking loose. We still have misguided fools saying it only kills 1-2% of people infected, and thus the best approach was letting the virus kill a few million people. Trump was one of them and Fauci held him back from doing and saying some really dumb stuff (mostly held him back--there's no restraining a natural genius like The Donald). So Fauci probably saved a few tens or hundreds of thousands of American lives by getting the government to institute changes that bought us time, which turned out to be enough time, amazingly, to develop several vaccines, which will likely save most of our sorry asses
. Although not the sad sacks who think it affects women's fertility or contains a microchip that will make you sound and think like Bernie Sanders.