ESPN has a breakdown of the rules that were recently distributed to players regarding who they can invite as guests.
These people must be family or long term personal friends of the players.
Guests must quarantine at home for three days, then fly to Orlando and quarantine for an additional four days, or they can quarantine the full seven days in Orlando.
As far as who can be there, each player will be allowed to bring four guests, though that appears to mean four adults as adding children means a player could invite a few more people.