Wrong. DVR ratings are counted. T.V guide lists the amount of shows watched live and on DVR within 3 days. I've seen several articles over the years claiming DVRs have actually helped certain shows viewership because people are able to watch it on their own schedule so are more likely to be able to follow shows easier.
I guess if you record something and just don't watch it for a long time that might not count but I would assume most people interested in a show watch it pretty quickly like I do.
Ratings that include people watching shows on their DVR within 3 days is called Live+3 and has only begun to gain importance because the networks tried their best to convince the advertisers to accept those ratings a few years ago. But for many years the advertisers didn't really consider Live+3 ratings because people can just skip through adverts.
Live+7 which includes ratings of people who view shows on their DVR within a week are not really considered when calculating advertising rates. Because of declining ratings for all shows every year, networks are trying their best to convince advertisers to now consider a show's Live+7 ratings when calculating rates. It still isn't accepted by advertisers.
DVR's can increase popularity but they do not necessarily increase Live ratings for shows. This is the most important thing for a show. You'll notice that today shows are no where near as huge as they were in the past. This is because of all the alternate viewing methods available and all that lowers a show's Live ratings, thus lowering advertising rates.