I make money from a variety of sources on it, including affiliate links, sponsorships (I recently had some success with http://upstart.me on this front), donations from readers (both Patreon and PayPal, because folks want options), banner ads, and fees for syndicating the content to outlets like Vice's Motherboard.
The pieces are written more like stories than link roundups, giving them an evergreen appeal. This week I wrote about the history of the 911 system; last week I wrote about CGA graphics and Windex. It actually has a smaller profile than my last project, ShortFormBlog, but it's more sustainable from a financial and work-life balance perspective.
Last month, I did a T-shirt sale with the help of a vendor (Vacord Screen Printing, http://vacord.com) and made a few hundred dollars through that.
All of this together is not enough to stop me from working a day job, but the mixture of sources and the fact that I syndicate content helps build exposure and ensures that if one source is weaker than another on a different month, the whole machine doesn't fall apart.
If you want to run a profitable newsletter, be willing to rely on more than one revenue stream.