There's a lot riding on Apple earnings Tuesday, including the potential for it to jump-start the tech sector — and possibly the market — if it issues a strong report with good guidance.

Apple stock traded up more than 1.8 percent Monday to $165.26 per share, ahead of its Tuesday afternoon earnings and amid chatter that it could announce a big stock buyback.

Apple stock is the largest by market cap, at $838.5 billion, and its decline has been felt. It was off 1.5 percent in April, but it has declined 9.9 percent from its March high, amid worries that iPhone sales will be soft.

Some big-cap tech companies already have reported earnings, and stocks have had lackluster performances. The hottest group in the market, FAANG, has had a choppy ride, due to regulatory concerns and fears that profits could be peaking.

However, FAANG members Facebook, Amazon and Netflix all gained solidly in April after good earnings. Google parent Alphabet was down 1.8 percent for the month.

"[Apple] still enjoys the biggest weighting in both the S&P 500 and NASDAQ 100 and therefore wields tremendous influence over the broader price action," writes Jeremy Klein, chief market strategist at FBN Securities.

"Shares of the tech giant have lagged the usual suspects of high fliers and sit at the same level from last summer. If [Apple CEO] Tim Cook can appease analysts by speaking effusively when delivering his profit and sales forecasts, then any lingering volatility should start to subside," he added.

Apple's earnings also come at a time when tech's leadership is in doubt because of its recent soggy performance. The S&P tech sector was flat for April, while the S&P 500 was up 0.3 percent.

"It's a big-cap stock. There's a lot of focus on these FANG stocks, and Apple has a ton of suppliers that rely on it. Smartphones are a huge market for [semiconductors] overall," said Peter Boockvar, chief market analyst at Bleakley Financial Group.

"In years past, Apple was its own asset class and what happened to Apple was specific to Apple. I just think nowadays the market is less forgiving if an important stock falters," he said.

When Apple declined, it took others with it. The S&P semiconductor and chip equipment subsector was down 4.4 percent in April, though it is up 30 percent over the past year. VanEck Vectors Semiconductor ETF was down 6.8 percent in April, its worst month in nearly three years.

Apple is expected to earn $2.68 per share for its fiscal second quarter, up from $2.10 a year ago, according to Thomson Reuters. Revenue is expected to come in at $60.9 billion, up 15 percent from a year ago.

Just based on earnings, the tech sector should be heading higher, said Keith Parker, chief U.S. equities strategist at UBS. "I would say the net mix for tech has been very positive for earnings and upgrades and outlooks, and the magnitudes of beats we're seeing."

"We have a few more reports," he said. "As we move out of this earnings season, the outlook for the sector looks very strong."

Parker had been expecting tech to lag temporarily but not the type of selling it has seen recently. An earnings beat or miss by Apple would be significant.

"I think it is a factor, and it helps set the tone for the sector," he said. "The weighting in the index is very large. You've had the stock pull back a bit and underperform. It's a very large stock with a big weight."

J.P. Morgan global strategists said the stock market could suffer if the tech sector "stalls out."

In a note Monday, they said U.S. tech has become expensive and technology earnings have "massively outgrown earnings for the broader market in this cycle." As a result, "it will be progressively more challenging for the tech sector to deliver significant EPS [earnings per share] growth rates, given the substantial EPS base currently, as well as the mounting regulatory uncertainty," they wrote.