You aren't gonna suck me into the "is she a whore" debateI don't think that's right. In the US people don't get tax rebates for donating to charity. They just shrink the income they have to pay taxes on. And she doesn't have much income so I don't get how she's missing out on much.
Who is an accountant here?
@Alpha Bullcock will know this.
But yes as @Delirium said, it's limited to a percentage of your income (usually 30, sometimes 50), which you can offset with the donation, essentially making that amount non-taxable.
That's probably why Johnny wants to break it up over several years - he may not be pulling in the >$25M this year that he would need to in order to make the $7M fully deductible. Or he is, but he doesn't have the "room" without hitting the cap.