I don't want to bet now, it's hard to figure a fighter like Ruis but for me Joshua will win by a knock out I just don't know the round because Joshua is not the kind of fighter who will go for knock out right away, he si very patient and calculating and will only get a knock out after beating his opponents to the punches.
He is really calm and never worried about KO. He usually looks for opportunities in the middle of the fight and launches a strong attack.