It isn't a pay cut. His total compensation is based on company performance via long-term stock grants, and they likely just had a lousy 1st fiscal quarter after several non-stellar quarters which both reflect poorly in company performance and stock price. He may even be getting the same number of shares, they are just worth 30% less today.
Executive pay swings pretty heavily toward "Monopoly money" - it sounds great to get x million shares, until you realize its paid out over the next decade, contingent on company performance, contingent on you staying in the role, and that you will have a heck of a time selling those shares before you leave due to the signal it sends the market and because of insider trading regulations.
Thats why it is rather disingenuous when you hear journalists talk about some exec's compensation package theoretical value in an article about a layoff. Thats typically stock which has lost a lot of value, paid off based on performance metrics that they obviously won't hit. They likely have most of their net worth based on the company stock they own, which just took a big hit.
People cry for the unjustness of them not sharing that money with the laid off workers, but it's obviously not real money. And the executives often ask to be paid with more Monopoly money rather than real cash, if they believe in the company they help run.
But back to a reduction in compensation to reduce layoff volume - you do layoffs to reduce operational expenditure. IANAA (I am not an accountant), but I don't think compensation hits as an expense until it is realized. If true, that would mean there are a lot of games you could negotiate which wouldn't decrease the compensation, but rather just defer it.
Apple tends to run very lean on teams however, so I have a hard time imagining them letting people go except maybe in retail. Instead, they'll just keep making it hard to hire replacements to encourage teams to operate more lean. They should have enough cash to keep paying people, as long as they can justify it to Wall Street.