Yes you can.

Confluence groups and group members can be synchronized with the corresponding microsite groups and their members by site administrator. If site is integrated with Gilly (confluence cloud), site admin will find a menu option 'Import from Confluence' under Users menu. 

Click 'Import from Confluence', It will list all confluence groups and members count in these groups. You can select groups to import that group and group members. [Note confluence reserved groups can't be imported)

Automatic group users sync option is also available, If auto sync is enabled for a selected group, system will automatically sync group members periodically.