Apple's strategy to bank on big stars, including Jennifer Aniston and Jason Momoa, to attract subscribers to its new video streaming service does not guarantee success, according to former Showtime CEO Matthew Blank.

"It's not necessarily the path to glory," Blank told CNBC's "Squawk Box" on Friday, the day Apple TV+ launched with original programming including "The Morning Show," starring Aniston, and "See," starring Momoa.

Blank compared Apple's bet on well-known Hollywood actors and actresses with Netflix's success with unknown talent. "Who was the star of 'Stranger Things' before it was on the air?" he asked, rhetorically.

The young cast of "Stranger Things," including Millie Bobby Brown, became household names because the show was so good and got popular, not the other way around. Netflix's introduction of lesser-known talent through its originals has paid off thus far, so much so it even mentions the numbers of its stars' Instagram followers in its earnings reports.

Apple TV+ becomes the latest entrant to the streaming wars dominated by incumbents Netflix, Amazon and Hulu. Soon-to-be rival Disney+ launches later this month, followed by Comcast's Peacock in April and AT&T's HBO Max in May.

In an effort to woo viewers, companies are offering various freebies — for example, Verizon customers can get Disney's service for free, and AT&T and HBO subscribers can get free HBO Max. Apple TV+ will be free for a year with the purchase of an iPhone, an iPad, an iPod Touch, an Apple TV streaming box or a Mac computer.

However, Blank said the flood of initial free subscribers could be a problem for investors. "That's going to make it really hard to say if any of these strategies are really successful."

Earlier on "Squawk Box," Gene Munster, co-founder of start-up funding and research firm Loup Ventures, said Apple TV+ will "probably add about 200 million free subscribers." Munster was a Wall Street tech analyst for years before starting Loup.

Apple has also reportedly spent billions of dollars on content for the service, in a TV-show and movie arms race with rival streamers. Netflix, for example, has planned $15 billion in content spending for 2019.

Netflix's latest big splash is Martin Scorcese's $159 million gangster epic, "The Irishman," about hitman Frank Sheeran, who claims he killed Teamsters boss Jimmy Hoffa in 1975. Robert De Niro plays Sheeran. Al Pacino plays Hoffa.

"The Irishman" debuts in select theaters Friday before becoming available on the Netflix streaming service on Nov. 27.

Disclosure: Comcast owns NBCUniversal, the parent company of CNBC.