There will not be any reference to Pewdiepie in A Machine For Pigs. It is never going to happen.
I have watched Pewdiepie's Let's Play of The Dark Descent, and I enjoyed doing so, because he seemed to be taking the game somewhat serious, acting silly only to gain courage to press on. I do not enjoy watching most of his other custom story playthroughs because I feel he is putting too much emphasis on silly behaviour and completely derails from the original atmosphere of the game and story.
One reason why Pewdiepie will not have a reference in the game is because it is the kind of game and story which would never make references to the daily world as we know it, including the community and playerbase. Another reason why I strongly doubt Pewdiepie being referenced to in the game itself is that it would contradict to the atmosphere and feeling of the game. He might make me smile with references like "Mr. Chair", "barrels" and "Stephano", but having this part of the game would really kill horror and atmosphere, I feel.
That being said, after I have played through A Machine For Pigs, I look forward to seeing Pewdiepie play it, and many others!
Radidsh is my alternate name. Hungry for horror games? Check out my channel!