Apple's earnings report, due after the bell on Monday, will shed some light on just how its iPhone sales are actually doing.
The tech giant, which released its iPhone 5S and iPhone 5C in late September, is expected to to announce iPhone sales above 34 million, said Ramone Llamas, a research manager at IDC.
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"About 34 to 35 million, that seems right about on track. Anything higher is going to be a huge surprise, but anything lower than that on the opposite end is going to say how soft that demand was in those July and August months," he said on CNBC's "Squawk on the Street" Monday.
Apple's release of two new iPhone models this year has also spurred some concern about gross margins.
"Obviously, the lower priced phones have lower gross margin opposed to the higher end phone so how is that going to impact gross margin going forward. So I think that is a key issue going into this quarter and obviously next quarter, which will be the holiday season," said Dan Morgan, Synovus Trust senior vice president and portfolio manager, on "Squawk on the Street."
In addition to lower margins, some analysts have reported that Apple's iPhone 5C hasn't had strong sales because the $100 price difference isn't enough of an incentive to opt for the cheaper model. However, other analysts argue that softer iPhone 5C sales means stronger iPhone 5S sales, which is actually a positive because it translates into stronger margins.
(Read more: Nobody seems to want Apple's iPhone 5c)
According to Morningstar, however, the real number to watch is the first-quarter guidance for December, since that will be the first full quarter look into iPhone demand.
Another thing to watch in the earnings report will be iPad sales, Morgan said.
Last quarter was the first time the company reported negative growth for iPad sales, he said. If Apple's iPad sales do not exceed 13 million this quarter then it will be the second negative consecutive quarter of growth, he noted.
(Read more: Apple reveals new iPad Air, iPad Mini )
However, Apple is expected to sell about 14.5 million iPad units, according to BGC Financial.
Apple's stock has been under pressure as competitors like Samsung, which power their devices off Google's Android OS, continue to chip away at the company's smartphone and tablet sales.
Some analysts predict it will take a completely new product category, like a smartwatch or a TV, to revive the stock. Another possible catalyst for the stock is a deal with China Mobile to carry the iPhone, according to analysts.
Apple is expected to post earnings of $7.96 per share, down from $8.67 a year ago and revenue of $36.8 billion, up from $36 billion during the same quarter last year.
—By CNBC's Cadie Thompson. Follow her on Twitter @CadieThompson.