Not quite what it seems
The hiring in the US they promise over the next five years is actually slightly less than the hiring they've done in the US over the past five years, so no additional benefit from the tax cut. The capital expenditures they are promising in the next five years is 1/3 of their projected capital spending (using the last couple years as a baseline) and Apple makes 36% of their revenue in the US so that's pretty much exactly what you'd expect and again nothing extra from the tax cut.
The main reason they're doing this is to counter the inevitable backlash they'll get when they announce what they plan to do with the bulk of the $200 billion after tax amount they're bringing home. They're going to increase buybacks and dividend growth, i.e. return it to shareholders. It isn't going to result in any more jobs created or investment made in the US than if the tax law hadn't passed and they had to keep that money overseas.
Still that $38 billion, and the tens of billions from other companies bringing money home, will create a one time drop in the deficit for 2018 which I'm sure Trump will take credit for. And then when it inevitably goes back up again in 2019 because that one time shot in the arm is over, he'll blame the democrats, or Mueller investigation, or whatever.