Is this RBTC a clone of the original Bitcoin like most bitcoins on the etherum network with a wrap?
and I have seen several times of RSK chains such as etherum which has a smart contract with several token bases such as stable coins, I want to ask how many circulations of RBTC are now available in the market?
It is a sidechain, and is not built on the ETH network, it's built on a different (albeit highly compatible with ETH) network called RSK network. There are multiple coins developed on top of RSK as of now, most notably RIF, MoC tokens and others.
You can check circulating supply at any time on the RSK explorer, top of the site, here:
https://explorer.rsk.co/