Yes, cable had ads from day one (as the first sentence of your article hints when it notes that cable was never conceived as ad free.) Originally, cable carried the exact same (ad supported) broadcast channels as were available by terrestrial broadcast; it was a way to get them when you weren't in a location with good reception (which was fairly common, at the time cable originated, places that weren't close to a major market center with a flat line of sight to it; stations weren't expending more power to broadcast than was needed to meet the big markets.)

That article is actually quite odd; the then-existing cable-only channels it mentions were mostly also commercially supported from day one, the ones they report on considering commercial models are channels preparing to go online, not then-operational ad-free channels. While they point to a public expectation of ad-free cable, they don't point to any actual history outside of premium channels (that generally remain ad-free), and other than public access channels, few non-premium cable channels were ever ad-free (except PBS broadcast channels carried by cable operators, when PBS had public funding that allowed it to operate ad free, but that had nothing to do with cable.)