I am advised by Revenue that, based on payroll data submitted to Revenue in 2021, the total number of workers that paid PAYE Income Tax in 2021 is approximately 2.53 million and the total number of workers that paid Universal Social Charge (USC) in 2021 is approximately 2.63 million. It should be noted that these figures represent workers that paid Income Tax or USC through payroll in 2021, rather than representing those with a final tax liability.
Revenue publish a breakdown of net receipts by tax head which can be located at the following link - www.revenue.ie/en/corporate/documents/statistics/receipts/net-receipts.pdf
As shown in this publication, in 2021 PAYE income tax amounted to €18.7bn and PAYE USC amounted to €3.7bn.