I am advised by Revenue that a Ready Reckoner providing estimated impacts for potential changes to a wide range of taxes and duties is available at www.revenue.ie/en/corporate/information-about-revenue/statistics/ready-reckoner/index.aspx.
The Ready Reckoner provides, on page 5, the estimated yield associated with changes to the USC rates outlined by the Deputy in her question. The measure would yield an estimated €171 million in a full year.
Please note that the costings for changes to the 8% rate as set out in the Ready Reckoner include those paying the 3% surcharge on non-PAYE income exceeding €100,000 in a year.