1. to account for; to make up; to take up
不安の声が大半を占めている。Voices of anxiety account for the majority.
2. to occupy (a place, position, etc.); to hold (a rank, seat, etc.)
北の壁際を占めるのはベッド。What occupies the space against the north wall is a bed.
3. to occupy (one's mind, heart, etc.); to weigh (on one's mind); to grip (e.g. one's heart)
その笑みが、あの日からなぜか頭の中を占めている。For some reason, that smile has been occupying my mind since that day.
4. to gain; to secure; to obtain; to win