Basic visitor information

Hi there

Looking for some information please. Wondering if there is a plugin available that would allow me to have a basic form that a visitor would have to enter some basic details or click to view annonymously before letting them proceed on a particular page?

I use a page on the site for Live Streaming and although I have put a simple chat facility in place it would be good to have a means to accurately find out how many people are viewing the stream at the time.

A website where they have what I’m looking for once the details are entered fades the form out to the live stream when it’s either completed or clicked to just view the stream.

Thanks

Colin