Fact check?

Having a hard time verifying the numbers in this OP I read?

"Fact is just bolstering the IRS could by itself pay for it. Consider the tax gap — the difference between what the government expects to collect in taxes and what it does collect. The latest IRS estimation is about $500 billion a year in legally owed taxes goes uncollected . Every new IRS auditor hired could bring in over 10X their salary of unpaid , legitimately owed tax revenue."

Can anyone help verify this argument for new IRS hires?