Can a friend see how many times I have looked them up using Find My Friends

No.

When sharing location with friends using Find My Friends, the other person doesn’t know how many times their friends have looked them up. They don’t get any notification or there isn’t any log of lookup incidents made available to them.

The location is sent from the friends device only when you request to see it. The location isn’t transmitted on a regular interval.

For more information on setting up and using Find My Friends, it is advised to go through the Apple support article, Set up and use Find My Friends.

Do note that your friend(s) can choose to stop sharing their location at any time and can also choose to share their location using the device of their choice (e.g. if they are also using an iPad along with an iPhone and signed-into it using the same Apple ID, they may choose to share their location via the iPad. This may differ from their current physical location).

A couple more important points to note from the article:

1. You can follow up to 100 friends.

2. Your location is sent from your device only when someone requests to see it. Your location isn’t transmitted on a regular interval.