The board runs on 3.3V, the rough current consumption figures are
Board on, processor in reset mode, all peripherals off: 50mA
Board on, processor active, all peripherals off: 200 mA
Board on, processor active, lora listening: 500mA
Board on, processor active, lora transmitting+(wifi/ethernet): 1 A
There will be conversion losses at the onboard dc/dc converter, so a 12V power supply will need to supply at least ~333mA for the gateway to work properly.
These figures are rough integrated averages. This means that the peak currents of all peripherals on board, and thus the total power consumption can differ heavily.