They claim that English "Japan" came from Italian "Gaipan" due to "Gi" sounding like "J", apparently failing to realize that they misspelled "Giapan" twice, don't make the connection to the "Cipan" in Marco Polo's "Cipangu", imply that Italians traded with Japan despite Portuguese and later Dutch traders monopolizing most of the trade, and most importantly don't even mention the Middle Chinese pronunciation /ȵiɪt̚ puən/ of 日本, which gave rise to both "Nippon" and "Japan" due to different sound changes affecting ȵ differenty in Japan and China.

Wiktionary' etymological explanation is much better: https://en.wiktionary.org/wiki/Japan#Etymology