Couric has just over 6 million viewers per night, which is not that far removed from O’Reilley’s 4 million viewers on a good night. Plus the 3 million that watch Beck at 5 pm, are not the same 3 million that watch O’Reilley at 8 pm. If you add up all the viewers for cable news throughout the day, it will probably trump the 6:30 newscasts from the networks. People don't feel the need to watch the network news at 6:30, in part because they have already watched the news on the cable news(mostly Fox) earlier in the day.
Is Fox news taking viewers from the networks? Of course.
You realize that Bill O'Relley and Katie Couric aren't on at the same time, right?
Couric competes with Special Report, which manages about 2.4 million ever night, half of what Couric alone averages.
"Is Fox news taking viewers from the networks? Of course."
Who said that they aren't. But, whatever FNC is taking from the networks is only a TINY fraction of the viewers that network news has lost the last 20 years. Which underscores my original premise - Content isn't the problem for the networks, technology and simple demographics is the problem.