If you say you "are not much for something" it means you are not in favor of it. For example, "I am not much for spicy food/reading books/social gatherings." would mean that I do not like these things. I do not think of them favorably. It is the opposite of the American idiom to "be big on something" (which means to think something is good or important). We use "not much for something" to express dislike or disdain. I hope this answer helps! Please let me know if you have further questions.

From this context it is clear that the man in the example does not like surprises. However, I have not read or heard this expression "he's not much for surprises" before. I would instead use the expression "He's not one for surprises" or "He's not big on surprises". These are more natural ways of saying "He does not like surprises."

He doesn't really like surprises.