How the Spotlight view counter works
Every public Spotlight has a view count that Snapchat keeps up to date all the time. This page reads it from Snapchat's own Spotlight page every few seconds while you have it open, together with the likes and shares, and rolls the digits to each new reading. It never guesses what happens between two readings.
Views are counted the way Snapchat counts them. Some creators hide the view count of their Spotlights; the page then says so and shows the likes only.
Where the numbers come from
From Snapchat's public page for that Spotlight. We read it at most once every 5 seconds per Spotlight, however many people watch the same one, so the number can be a few seconds behind the app. When Snapchat asks us to slow down, the last reading stays on screen with its time and the page catches up by itself.
Put it on your stream or website
Open a Spotlight and use Embed code for a widget on a website, or OBS link for a browser source. The widget reads a new number every 5 seconds while it is on screen and never shows ads.
Follower counts are different
Subscriber counts do not move by the second: Snapchat rounds them to the nearest 100 and updates them a few times a day. The Snapchat follower count page shows those, with the most followed accounts.