The ground stations I saw on the map had 2.1GHz of uplink and 1.3GHz of downlink. If we assume 4b/hz (about as efficient as LTE/WiFi), thats 8.2Gbps up and 5.2Gbps down. I'm not too sure to what extent they can use MIMO techniques, but if they can, throughput could be multiplied by the number of MIMO channels.
I don't think you'd have much benefit of MIMO on a connection that's line of sight like this. MIMO is all about making the most of separate connection paths through reflections from walls, buildings etc. But in this case there'll be only one path.
