They sell ad space on their website to player-run groups in EVE. These groups pay ISK for the ad space, the in-game currency. [1] That ISK is paid to writers for each piece they write.
The ships they report from are cheap as chips, so not really a sourcing concern given that their reporters need to be hardcore enough EVE players to understand and write about their subject matter—and as a result, would have made enough money in the game already to afford the type of ship you need to do this.
[1] - https://newedenreport.com/2018/06/01/new-eden-report-sponsor...