Can NaOH and pepsin cause digestion?

No is the answer. Sodium hydroxide is is such a strong alkali that it will 'burn' the cells just like acid does. So it is not found in body. Instead you have sodium bi carbonate. But you have very strong acid in stomach. Hydrochloric acid. Imagine acidity go on increasing ten times as you go from 6 to 5 and 5 to 4. And pH in stomach is 1 to 2. (Why does not stomach is 'not' charred at this pH ?) Pepsin works in high acidic pH only and almost stop working at 5.5 pH. So no question of digestion in sodium hydroxide, which is strong alkali with very high pH. If you lower the pH pepsin starts working again.