ΔE 21.3, loose: different enough that you should pick on purpose. Gloomy Violet is noticeably darker, much more saturated, warmer than Occultist Cloak.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Gloomy Violet is noticeably darker, much more saturated, warmer than Occultist Cloak.
The same difference applies the other way round: Occultist Cloak is noticeably lighter, much more muted, cooler.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Occultist Cloak on the colour wheel See Gloomy Violet on the colour wheel
All matches: Occultist Cloak equivalents · Gloomy Violet equivalents