It would not be possible to get 8, you would only get 6.
Explanation : 1 port on each hub must be used to connect it to the other hub. This is generally termed an uplink port. Some hubs/switches have dedicated uplink ports (dlink dss-8+ for instance) so you'd be able to get the 8 total if you used to 4 port hubs that had this feature. However, most don't so 6 is more likely.