Company links can be shared by both permission level or to individual staff members and staff groups on a link by link basis.
To find out who has access to a link, navigate to the general tab of your company settings. Scroll to the bottom of the page until you come to your company links.
Click on the admin cog to the far right of the link you wish to view and select edit.
You can see who currently has access to the link under link visibility. You can also amend these permissions from here.