Is it possible to get the amount of times an URL is received by a device from the proximity beacon API? I want to know what the click through ratio is of the broadcasted URL.
That depends. If you write your own app that scans for Eddystone-URL beacons and triggers some content (e.g., the web page itself) off of that, then naturally you're in full control and can implement this kind of analytics. Though it'll only apply to people which installed the app.
If you rely on Chrome for iOS, or the Physical Web iOS and Android apps to discover the Eddystone-URL beacons, then these apps do not provide any such numbers.
However, both Chrome for iOS and the Physical Web apps do fetch some metadata about the URL they detect, such as the page title and page description, without the user first clicking on the link. So there's a slim possibility that you could filter such requests out (they will be made by the Physical Web Service, or some similar "bot"), separate them from the actual visits, and do analytics based on that. Most likely however, this "bot," or the proxying service (which is there precisely to prevent this kind of tracking, and protect the user's privacy), will also do some caching, so you'll see fewer requests than the actual number of times the URL is received by the device.
And finally, dropping to a lower level, a note: most beacons are uni-directional, i.e., they broadcast information, but don't receive any information back, so beacons themselves usually can't count the number of packets on the receiving end. (I guess you could technically use the Bluetooth "scan response" mechanism to do that, but it would require custom beacon hardware/firmware.)