Apple stock, Samsung stock

A recent poll shows strong demand for Apple's upcoming iPhone 6.

As Apple (NASDAQ:AAPL) gears up to launch its iPhone 6 lineup this fall, the tech giant appears set to enjoy at least one huge catalyst to reinvigorate its growth: the upgrade cycle.

At least, that's what a recent survey from analysts at RBC Capital Markets indicates. RBC recently polled over 4,000 consumers and found nearly half of those planning to upgrade their smartphones in the next three months are "inclined to purchase" an iPhone. By comparison, "just" 37% favored Samsung's (OTC:SSNLF) Galaxy series devices.

What's more, an impressive 64% of Apple-leaning buyers say they'll opt for an iPhone 6 and 26% insisted they'd be willing to pay another $100 for an iPhone 6 with a larger, 5.5-inch display.

Of course, Apple wouldn't necessarily complain if a larger chunk of consumers decided to continue to buy its soon-to-be-older iPhone 5s and iPhone 5c models. That would, after all, still serve its end game of driving billions in revenue to its coffers in the form of digital app and media sales. But seeing such a high percentage of iPhone 6 adopters will be great for Apple's gross margins, which have already enjoyed an uptick in recent quarters thanks to buyers' acceptance of higher-than-expected iPhone 5c pricing late last year:

Apple stock, AAPL Gross Profit Margin (Quarterly) Chart

AAPL Gross Profit Margin (Quarterly) data. Source: YCharts.

Worse yet for Samsung, a full 35% of users who don't currently want to purchase an iPhone said they would do so if Apple offered one with a larger form factor.

Then again, we've already established Apple knows all too well the iPhone 6 needs a bigger screen. But as its widely anticipated debut nears, Apple investors should be excited to hear confirmation of this preference coming directly from the consumers on which they rely to drive their company's growth.

So what kind of growth should we expect? If RBC's supply chain checks prove accurate, Apple is gearing up for year-over-year unit growth of 15% to 20% for the December quarter. Considering Apple sold a then-record 51 million iPhones in its most recent fiscal first quarter ended Dec. 28, 2013, that means an expected range of 58.65 million to 61.2 million iPhones sold this time around -- even the low end of which would easily set a new all-time quarterly high mark for the folks in Cupertino.

It's important to note, however, that this is how many iPhone 6 devices Apple expects to sell in their debut quarter. Whether these big numbers actually pan out will depend greatly on just how impressive Apple's latest round of innovations turns out to be. But, really, it's hard not to be optimistic after Apple Senior VP Eddy Cue recently boasted of "the best product pipeline that I've seen in my 25 years at Apple." If that holds true, Apple stock should be set to continue to handsomely reward patient investors going forward.