Not quite. The extra seats only provide additional revenue when the flights would have otherwise been full. From the article, the average flight is only 80% full, which means those six extra seats aren't providing any additional revenue.
To determine the actual revenue increase from those six extra seats, we would have to know how frequently flights have less than 6 empty seats.
To determine the actual revenue increase from those six extra seats, we would have to know how frequently flights have less than 6 empty seats.