those don’t look like they are indented properly - is that just the way they copied in or are they really like that in you config?
I had no problem with sass with jekyll but it was not nested like that.
As for gulp here is something i used to use that is fairly simple:
you would need to have node installed, and then it looks like I left out the package.json file that would load the couple things required by gulp - as well as gulp itself.
I also just made this post which links to another page on my site about what I am doing now - and in that thread is also a link to a post from @mmistakes about the same thing - though he is way ahead of me.
This is a good basic tutorial: