* TCS shares gain after Oct-Dec earnings
* CLSA, Jefferies upbeat about outlook
* Barclays warns about revenue growth (Adds comments from analysts)
MUMBAI, Jan 15 (Reuters) - India's largest software services exporter Tata Consultancy Services Ltd (TCS) gained the most in more than eight months in Mumbai trading after posting better-than-expected earnings and prompting a raft of analyst upgrades.
HSBC upgraded TCS to "overweight" from "neutral," and "modestly" increased its profit outlook for the year ending March 2014 by 2 percentage points, citing improving margins and an expected rise in demand.
CLSA described the quarterly earnings as "picture perfect" and upgraded the stock to "outperform" from "sell."
TCS reported on Monday a 23 percent rise in quarterly profit from a year earlier and reiterated it should beat a closely watched industry growth forecast.
Its shares advanced as much as 4.9 percent on Tuesday, the most since April 24 last year, and were up 2.1 percent as of 0621 GMT.
However, Barclays Capital kept TCS at "equalweight," saying the company's revenue growth of 3.3 percent quarter-on-quarter was slightly below its forecast.
"While passing muster versus our estimates, TCS' results paled compared to the revenue growth posted by Infosys last week," Barclays analysts wrote in a note.
Infosys posted a 4.2 percent gain in revenue for the quarter ended December compared with the previous three months.
The mixed analyst reaction to TCS came after the software services exporter consistently topped estimates with its earnings last year.
Other analysts reiterated their bullish calls on TCS, with brokerage Jefferies maintaining a "buy" rating.
"TCS has delivered quarter after quarter, justifying premium valuations over peers. Our view has been that 2013 is likely to be a better year for Indian IT as far as demand is concerned," Jefferies wrote in a note.
Shares in Infosys fell 0.4 percent after surging 21 percent since Friday when the company announced its third-quarter earnings. (Reporting by Rafael Nam and Abhishek Vishnoi; Editing by Ryan Woo)