I know that the owner of a repo is able to see a fork request when one is performed. But what about a clone? Can the owner of the repo see when someone clones it?
The question is too general, but let me answer the question as it stands now.
Can the owner of the repo see when someone clones it?
No, they cannot. If I go to one of your repositories and clone it to my local hard drive, you can't see that. And why would you want to? Likely there are many clones of your repository.
Know that clones can live on other systems than github.
Now, will the owner know that someone forked their repository on github itself?
Yes, they will, assuming they pay attention.
I did the following:
This is what I see on my first page after logging in:
If I do the following:
Click on the small 1 to the right of the "Fork" button:
Click on the "Members" tab:
Then I see this:
Conclusion:
Yes, the owner of a repository will see when someone makes a fork on Github, but no, they will not see it when someone makes a clone somewhere else.