There is no information from Apple about how iPhone 7/7 Plus is doing yet.
I've noticed that Forbes' tech "articles" these days are all basically blog posts. Maybe it's a move to get news and views out quicker, but the quality has really suffered. May as well read Gizmodo.
That said, I would expect that iPhone 7 / 7 Plus unit sales to trail 6s / 6s Plus sales, partially because of the loss of the headphone jack and partially because it is the third iteration of the same outward design, and most importantly because Apple this year suddenly decided not to release sales numbers. Apple claims the reason is because they couldn't accomodate demand, and I suspect that is true, especially for the new colours and the Plus. The Plus is the new king this year, whereas the prior two years the regular 6 / 6s were the bigger sellers. However, I also think the other reasons I've listed play into it.
But, I'm just guessing, and it seems Forbes' blog posts are guesses too. We'll find out more though in three weeks, at the earnings conference all. I do wonder though, even if the unit sales of the iPhone do fall, how much of that will be mitigated by the higher percentage of Plus sales. My GUESS is that overall iPhone revenue will still fall vs. last year, but it's not all doom and gloom like some want to believe, and things will change in 2017 with record sales again given that it will likely be a
completely new form factor.