Is paprika a suitable substitute for cayenne pepper?

I wouldn't consider normal paprika the best substitute for cayenne pepper but you could get away with it if nothing else was at hand. Paprika is very mild and it's mainly mais a colourant for a meal than a taste enhancer, however hot paprika would be an adequate substitute for cayenne pepper as it is very hot. If the focal point of the dish/recipe is the peppery heat/hotness, then I'd go with the hot paprika, black pepper or even chilli powder as a substitute for cayenne.

Paprika is a little too mild compared with cayenne, it really depends on what you are using it for, if it's just a garnish then yes you could get away with it, but as an ingredient I would use chili powder or even hot sauce or you could use crushed peppers. usually if it is an ingredient you want the kick.

it is but is stronger.
oh wat the hell... i have no idea what im talking about!