If you are a git user, you can install the theme and keep up to date by cloning the repo:
git clone https://github.com/dracula/gimp.git
Download using the GitHub .zip download option and unzip them.
cp -r ~/gimp/Dracula/ /Applications/GIMP-2.10/Contents/Resources/share/gimp/2.0/themes/
Preferences > Interface > Theme > Dracula : OK
Get updates about this theme and more. 5,986 people enjoy it.
This theme wouldn't exist without these people. Wanna help too? Check the repository on GitHub.