If you would like to have all of your "pitches" in a single repo you can absolute do that. As described in the Wiki:
"Sometimes you may find yourself wanting to build a series of related presentations within a single branch. Collectively these presentations may share common assets such as images, backgrounds, and even custom CSS styling."
For details see the following page in the GitPitch Wiki:
You might also be interested in support for modular Markdown which allows you to share not just assets but Markdown snippets across multiple presentations. See here:
"Sometimes you may find yourself wanting to build a series of related presentations within a single branch. Collectively these presentations may share common assets such as images, backgrounds, and even custom CSS styling."
For details see the following page in the GitPitch Wiki:
https://github.com/gitpitch/gitpitch/wiki/Asset-Sharing
You might also be interested in support for modular Markdown which allows you to share not just assets but Markdown snippets across multiple presentations. See here:
https://github.com/gitpitch/gitpitch/wiki/Modular-Markdown