It all depends on your workloads.
If you've got eight "light" users that work with some office documents, surf the 'net, send and receive a few emails, oversubscription is a non-issue. It might not even matter if the users are connected by gigabit or only 100 Mbit/s. You could even have 40 end nodes or more on a single gigabit uplink without any problem.
If you've got eight servers that are moderately-to-seriously frequented, or heavy users (moving large data amounts, video, ...) you'd want to make sure that there are no bottlenecks. Server backup may also run out of its window, so you'd need at least 2-4 Gbit/s uplink, the more the better.
In extreme, you've got a backup repository cluster where you'd want no potential bottleneck at all - that'd mean a 10 Gbit/s uplink (or for that matter, dedicated 10 Gbit/s to each node, 40+ Gbit/s uplink).
To better size your workloads it really helps to monitor the current links for a while. Ideally, you track daily traffic amount and height and width/length of the peaks. At least try to grab (or write down) the port counters once or twice a day.