Number of devices that an 8-channel GW can support

In the document " What are LoRa® and LoRaWAN®?" you state that: “A single eight-channel gateway can support a few hundred thousand messages over the course of a 24-hour period. If each end device sends 10 messages a day, such a gateway can support about 10,000 devices.” How do you calculate that?

The link to the document is given below.

Best regards Jes