* Yellen, new Fed chair, takes hot seat at Capitol
* Sprint's quarterly revenue increases, subscribers grow
* Futures up: S&P 6.3 pts; Dow 46 pts; Nasdaq 15.5 pts
NEW YORK, Feb 11 (Reuters) - U.S. stock index futures gained on Tuesday on hopes that the new Federal Reserve Chair Janet Yellen will reinforce the Fed's determination to halt the money-printing presses while assuring investors that a rise in interest rates remains a long way off.
* Yellen's prepared testimony on the Fed's semiannual monetary policy report will be released at 8:30 a.m. EST (1330 GMT). A hearing before the Republican-controlled House of Representatives Financial Services Committee starts at 10:00 a.m. (1500 GMT).
* Yellen, in just her second week in the job since succeeding Ben Bernanke, is expected to be cautiously optimistic after a mixed ream of data that has raised questions about the growth outlook for the world's largest economy.
* S&P 500 e-mini futures rose 6.3 points and were above fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures rose 46 points and Nasdaq 100 futures added 15.5 points.
* The central bank has cut its monthly bond-buying program by $10 billion at each of its last two meetings, reducing the total amount of purchases to $65 billion.
* Sprint Corp, the No. 3 U.S. mobile provider, reported an increase in quarterly revenue that was ahead of analysts' expectations and said it added wireless subscribers in the fourth quarter. The stock was up 6 percent in premarket trading.
* CVS Caremark Corp posted higher quarterly profit as it processed more prescriptions and benefited from the introduction of new generic drugs. The stock rose 2.5 percent in premarket trading.
* French cosmetics firm L'Oreal is buying 8 percent of its shares from Swiss food group Nestle for 6.5 billion euros ($9 billion), loosening their 40-year partnership and allowing both firms to boost earnings per share.
* U.S. stocks ended with modest gains on Monday as investors looked ahead to new Federal Reserve Chair Janet Yellen's first testimony before lawmakers.