Fewer than 20,000 Illinois millionaires would account for 80 percent of an estimated $3.4 billion in added income tax revenue under a graduated tax plan being touted by Gov. J.B. Pritzker, his office said in a release Friday. Per Pritzker’s projections, 19,939 Illinois taxpayers whose income exceeds $1 million would pay an added $2.72 billion in combined taxes to the state.