Expanding price-earnings ratios helped stocks soar last year, but in 2014 the market is more dependent on earnings, says Robert Doll, chief equity strategist at Nuveen Asset Management.

"This year the earnings are going to have to come through to have that proverbial good year for stocks," he told Morningstar.com.

Doll likes what he's seen during last year's fourth quarter and so far this year.

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"Despite some of the current economic data, the news from the fourth quarter [showed that] revenue growth finally picked up," he said. "We had, I think it was five quarters of basically zero, and now it's starting to pick up, which has pushed bottom-line EPS [earnings-per-share] growth up to very high single digits."

As for this year, "we need . . . some acceleration. I think we're beginning to get it," Doll said.

He thinks most of the economy's recent weakness stems from the severe weather in much of the country. "I think we have a lot more bad news to come on the weather stuff, including probably at least one more bad employment report."

Jeremy Siegel, a finance professor at the University of Pennsylvania, is bullish on stocks because of strong earnings estimates.

This year, earnings are expected to rise 20 percent for companies in the Standard & Poor's 500 Index, he told CNBC.

"If any of these earnings estimates pan out, and they are bullish, we're in about the fourth or fifth inning of this bull market," Siegel said.

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