An important thing for Korra was always going to be the viewing figures and ratings for the premiere to get a judge at how popular the show was and especially in comparison to ATLA.

We have got the numbers for the First 2 episode premiere

http://tvbythenumbers.zap2it.com/2012/04/17/debut-of-nickelodeons-the-legend-of-korra-draws-4-5-million-viewers/129568/

Korra got 4,548,000 viewers on it’s premiere, and a 1.01 rating in the Adults 18-49 demographic (which means that 1.01% of the nielsen universe that are aged between 18-49, 127,860,000 adults viewed Korra. In other words 1,291,381 in that demographic, the most prized in terms of ratings overall).

In comparison to ATLA this is excellent, as ATLA premiered with 3.47 Million and Korra is also higher than every episode of avatar except the 4 part finale which got 5.6 million. Also impressive given its early 11am timeslot.
So things are looking exceptional for Korra as the word will spread.

We won’t be posting the ratings of every episode as news, but they will definitely be mentioned on our forums.

They're All Dead :(