art
埶 centers on cultivated skill or technique, specifically art. The meaning is narrow and the kanji is rare, so treat its standalone sense as uncertain.
The historical development of 埶 is uncertain. The modern form visually combines 坴 and 丸, but the original component relationships are not clear.
The left side 坴 looks like a mound of earth, and the right side 丸 suggests something rounded. Picture a potter shaping a rounded clay vessel on a mound: the art of pottery.
For ゲイ, imagine a geisha practicing her art: gei -> ゲイ, and her refined skill matches the kanji's meaning.