Do we know if the (apparently Texan) organizer of that fundraiser is affiliated with the victims in any way, or is credible, or might that be a scam?
According to their about page [0], they're a licensing/localization company for Japanese animation. Looking at their catalog [1], they've localized various Kyoto Animation productions.
As other comments on this thread have pointed out, the company also shared the campaign on their Twitter account.