Sure. Take a married couple filing joint. The first bracket point for 1997 was $41,200. Taxable income (e.g., adjusted gross income after all deductions are taken) below that amount was taxed at 15%. Above that amount the rate was 28%. Suppose taxable income is $50,000. Then the tax (assuming there are no tax credits subtracted later) is 15% of 41,200 plus 28% of (50,000-41,200), or $6,180 plus $2,464, = $8,644. Now suppose the CPI is 3%. The bracket is adjusted up by that amount, to $42,436. (I believe there is some rounding but the basic effect should be clear.) The same taxpayers now have $1,236 more in the first bracket, taxed at 15% rather than 28%. The savings is 13% (28-15) of $1,236, or about $161. If a point is knocked off the CPI, the savings is only 2/3rds as much, or about $107. If .2 is knocked off the CPI, the taxpayer loses about $11 in savings. This may not seem like much, but with an excess of 100 million tax returns, it adds up to a nice piece of change. Probably enough to fully fund Head Start, for instance.
Note that the higher one's taxable income, the more is saved from indexing since portions of income are exposed to lower tax rates in each bracket. Conversely, the simplest, most powerful way to boost income tax revenue is to repeal indexing, or to reduce it (e.g., CPI-1!). Total lack of indexing in the 1970's probably had something to do with tax revolts and the ascendance of the Right, so it is possible to over-reach in this regard, but right now we'er at the other extreme.
The number who would end up in higher brackets depends on the concentration of taxpayers around the break points, and this data is not easily acquired. One has to derive it from the micro-data.
MBS