>Gettier's conception of knowledge as justified true belief (prob familiar to many philosophy undergraduates) implies that machines can't in fact accrue knowledge.

Nothing about the conception of knowledge as "justified true belief" implies that machines can't accrue knowledge.

For that to be the case "belief" would have to be defined in a circular way to exclude machines (which we can reject), or "justified" would have to be restricted to mean "based of observation of the external world".

The more general "based on observation of their input" applies to both men and LLMs.

That man can't know the bare direct facts of the world, just his own input (it's sensory experiences, and whatever second hand input he's given by other people), and for neither can he be sure they're absolutely true, or that he got right.

>The idea that knowledge can't be defined in a non-circular way is only plausible for someone with no familiarity with epistemology.

The idea that this or that epistemology restricts what can be the case in reality is only plausible for someone with no familiarity with epistemology.