The Dow led a surge in US stocks on Friday as upbeat earnings from Apple (AAPL) lifted spirits in the wait for the monthly jobs report, a crucial litmus test for interest-rate expectations.

Dow Jones Industrial Average (^DJI) futures jumped 0.8%, or 320 points, while S&P 500 (^GSPC) futures rose 0.4%. Contracts on the tech-heavy Nasdaq 100 (^NDX) were up roughly 0.7%.

All three gauges are poised to build on sharp closing gains as the market absorbs the flow of earnings before shifting focus to the marquee event, the April labor figures.

Apple's quarterly profit beat expectations, and it surprised investors with better revenue out of China than estimated in the face of reports of flagging iPhone sales.

While CEO Tim Cook talked up Apple's plans for AI development — a key focus this earnings season — it was the company's plans for a $110 billion stock buyback, the biggest in US history, that captured the market's attention. Apple shares rose 6% in pre-market trading, set to buoy the Dow.

The blue-chip index is also seeing a boost from heavyweight Amgen (AMGN), whose shares soared 14% as comments by its CEO suggested its obesity drug could take on market leaders from Novo Nordisk (NVO).

The April jobs report, due for release at 8:30 a.m. ET, could shift the mood, given the labor market is seen as setting the trajectory of inflation — the key factor shaping the Fed's interest-rate policy. Nonfarm payrolls are expected to have grown at a steady but decelerating rate last month.

Read more: What the Fed rate decision means for bank accounts, CDs, loans, and credit cards

Investors have reset their bets on the timing and prospect of a rate cut this year after Chair Jerome Powell took a more dovish tone than expected at the end of the Fed's meeting on Wednesday.