Not quite. "The sick man stayed in the hospital" "The sick man went to the hospital" "The sick man was recovering in the hospital" "The sick man resided in the hospital" Occupied often imples that it is filled or that a person lives there or controls it. If using the word 'occupied', no need to use the preposition. "The protest group occupied the hospital"

I guess it should be The sick man occupied a bed in the hospital , will be a good sentence.

don't think so. the sick man was taken to the hospital/hospitalized or there was a man, who occupied the hospital room (don't know your context)