The official wiki lists the following as one way to get influence:
2 influence for individual guild members completing an event or part of a personal storyline. (The per-player influence gained increases substantially with each new participating guild member.)
Does anyone know exactly how this guild bonus works? Does this mean if you have more than one guild member completing an event together, you each generate more influence for the guild?
Update: Appears that you get 20 influence if you do an event with one or more guildies together