Cushman had this to say
when interviewed at a Las Vegas convention appearance in 2013:
We were always told that 'Star Trek' was a failure on NBC. That is why they had to cancel it. I licensed the Nielsen rating for every episode. 'Star Trek' is winning its time slot quite often during the first season. It was NBC's No. 1 Thursday night show, beating sometimes the best competition that the other networks had to offer. And yet they said the ratings weren't good. They moved it to Friday nights. It was their No. 1 rated Friday night show. You don't cancel your No. 1 show.
He doesn't use the word "hit," but it is implicit here that the show's ratings were "good."
He also claims that since the show was NBC's number 1 program on Thursday and then Friday nights, the network couldn't have cancelled the series because of its ratings. I (and others) have already explained how this reasoning is problematic.
And here's another interview (at Trek Movie):
I became so obsessed with getting the ratings that I called Nielsen back and I said it in a way I hadn’t said it before. I said,” I’d like to license the ratings reports from the late 1960s” They then said, “Oh, okay we’ll switch you over to that department. What ratings are you interested in?” I said, “Thursday night, 1966, 67 and Friday night 67 through 69.” They said, “Okay, we’ll get back with you.” They called me back they very next day and said, “Yeah we’ve got them. How many do you want?” I said, “I want one for every week they said, “Okay here’s how much they’re going to cost…” I said: “Whaaa??? Okay well, maybe I’ll just take the one for the first run episodes and forget the reruns…” Although I did get a few of the reruns, just out of curiosity. So I licensed all these ratings, which set me back financially a bit, but it was like a lost treasure! I found out for Season One and the episode “Mantrap” had an audience share of 47 percent of the TVs in America running, were tuned into Star Trek. Quite often and usually most of the time it’s number in second place, and there is no shame in second place, and by the way, the show it’s beating almost every Thursday night is My Three Sons, which was considered a hit on CBS and went for another five seasons. The show that it’s losing to, was but not every week, ABC’s number one-rated series, Bewitched. It was the top show the network had out of all of their shows. Star Trek on more than a dozen occasions beat it; on other occasions tied with it, and on the rest occasions came in a close second.
His claim that "I found out for Season One and the episode “Mantrap” had an audience share of 47 percent of the TVs in America running, were tuned into Star Trek," is misleading. Obviously, only "The Man Trap" had that audience share, and Cushman doesn't point out they key fact that Star Trek
was up against a re-run on CBS and The Tammy Grimes Show
on ABC (which, as Maurice
points out, was such a colossal failure that it was pulled after only four episodes).
He complains that My Three Sons
went for five more seasons, but he neglects to admit that it finished the season with a higher average rating than Star Trek
(it was tied for the 29th spot among the top 30 shows), and that it's ratings increased significantly in following seasons.
He goes on in the same interview...
I went further. I looked at the ratings of the shows before and shows after, on that night and found out that Star Trek was NBC’s top-rated Thursday night show — their biggest hit of the night! You don’t cancel your top-rated show! That was the show all the other shows are anchored to. But NBC tried to cancel it. And I’ll give you a peek into the future — in Book Two: They moved it to Friday nights, which is not a good night for a show like that, with the college audience, so obviously they’re trying to distance it from the audience, and it was still their top-rated show for that night. It was their top-rated Friday night show, and they tried to cancel it. But the network got buried in protest letters, so they renewed it, but then they moved to Friday nights at 10 p.m. to make sure it was dead. That’s called the death slot — that’s the worst time of the entire week.
He'll have to back up his claim that NBC "tried to cancel" the series after season two in the next volume; I certainly haven't seen any evidence of this. Also, his conclusion that NBC "obviously...[was] trying to distance it from the audience" is far from obvious. Indeed, it's nothing but author speculation.
And calling it NBC's "top rated show" as he does here is deliberately misleading. A quick look at the top 30 shows from 1966-67 shows a number of NBC shows, which, obviously, rated higher than Star Trek
(which wasn't in the top 30).