If you read my Denuvo thread you will see some one from 3DM give his opinion on how he thinks it works, plus how hard it is to crack.
It can obviously be cracked, but the time and effort needed simply isn't worth it. So they may have made this statement to keep the egg off their faces.
As Denuvo advances it gets tougher and tougher to crack.
There is no concrete way of seeing how it affects sales, either. Most of the information available online regarding the amounts of games is not correct.
The only people who could officially state how many sales they have made is the publishers, and they usually don't.
That said Denuvo must be working because it's being used more and more, and if something made no difference why would you pay for it?
I looked at some sales figures the other day for Fifa 15 and it has sold far less than Fifa 13, which was cracked. I find that interesting.
I feel that if some one was not going to buy the game any way they won't because they can't steal it. They'll just steal something else. It's that mindset you cannot change. Go over to Skidrow's site and read through the comments on ROTTR. It's clear that if you make something impossible to steal that it won't generate more sales just because people have to pay for it. They simply won't, as they never intended to in the first place.
For example over the years there are certain games that I have only played because I could steal them. Quite simply? they did not interest me or make me want to buy them. If I stole something and liked it? I usually always bought it because then I could get access to online play and so on. If I had never stolen Fallout 3 I would never have played it, because it was an RPG and I really am not a fan of RPGs. Once I stole it and fell in love with it though? I've now bought about five copies of it in various guises.
