MA EMAC and Supplemental Tax

A google search result says:

"The Employer Medical Assistance Contribution (EMAC) Supplement. The Employer Medical Assistance Contribution Supplement applied to employers with more than five employees in Massachusetts. The contribution was 5% of annual wages, up to the annual wage cap of $15,000, for a maximum of $750 per affected employee per year"  from https://www.mass.gov/info-details/learn-about-the-employer-medical-assistance-contribution-supplement

Have any of the impacted employees made $15k this year / been taxed $750 so far?

You can check using the Payroll Detail Review report, which itemizes each tax for each employee and shows the YTD history by paycheck with totals.