Questions like this don't make sense to me. People have human responses to humans suffering, it's impossible to say how therapists feel as if they are a homogenous blob. How do teachers feel about students? How do hairdressers feel about heads of hair? How do painters feel about walls? How do fishermen feel about fish? Actually, this is quite an interesting little game. Tinker, tailor, soldier, sailor. An individual client can make a guess about how their therapist might feel if they died, but beyond that, who knows? At best, it's a guess because no one knows how they will feel about a hypothetical situation. I think some people take comfort from the idea that their therapist would be devastated if they died. If you want to know if your therapist is affected by your life and interactions (and your hypothetical death), why don't you ask them?