The term 'high viewership' is correct and usable in written English.
You can use it when referring to the number of people who have watched a movie, TV show, livestream, etc. For example: The season finale of the show had a high viewership of over 10 million viewers.
During its run the show consistently earned high viewership ratings and won 29 Emmy Awards.
"Roseanne" will likely result in high viewership for a few weeks.
If the Casey Anthony trial is any indication, the high viewership will recede after this trial concludes.
Since viral videos can trigger network effects that are favorable to business, it is important to compare the two types of videos with high viewership.
Fox is tantalized by the potentially high viewership of a prime-time matchup between the teams that played in last year's American League Championship Series.
Simon Cowell thought he had banded together one of TV's most attractive teams, able to bring in a record high viewership for his 'singing' contest, The X Factor.
The record-high viewership for the interview with Bobbi Kristina — who turned 19 this month and whose father is the singer Bobby Brown — may put even more pressure on Ms. Winfrey and her producers to score exclusive interviews with celebrities.
Ratings out last week show sky-high viewership for all three — and that's manna from heaven in an industry whose numbers were tanking in 2014 and where average viewers are over 60 — while millennials cut the cord and stay glued to their phones.
It was the highest viewership total to date for the fledgling news program.
Some of the highest viewership of the show was among women 35 or older.
Trump correctly noted in his tweet that Fox News had the highest viewership of the night.
