How profitable is hip-hop culture worldwide, in terms of revenue per
year, based on an analyzation of album, movie ticket and video sales,
clothing and videogames?

You can't measure profitability exactly, that's down to how much
margin the companies make of the products you listed. It would
probably scare you to learn that!!

I would guess it's a multi million pound/dollar figure for sure though!!

Good luck finding out...