1 billion dollars clawed back, minimum of 250k tax debt.

So a minimum of 4000 individuals? Assuming theyre clawing back the full amounts owed in one go

edit

additional detail from another source

As part of larger efforts taking place, the IRS has stepped up activity specifically on 1,600 individuals whose incomes were more than $1 million per year and who each owed the IRS more than $250,000 in recognized tax debt. Since last fall, this IRS compliance effort has generated more than $1 billion in collections from this group, with work continuing in this area.

https://www.irs.gov/newsroom/irs-tops-1-billion-in-past-due-taxes-collected-from-millionaires-compliance-efforts-continue-involving-high-wealth-groups-corporations-partnerships

So 1billion from 1600 individuals, they pulled back on average 650k per person