Is it possible to see how many tokens has been sold so far?

Yes, here:

https://etherscan.io/address/0x6ccb56947ea1d6efdc81acfbacd8263ddfa9b202#readContract

getAttoTokensBoughtInICO: 557303897693922862106028

This is in atto-tokens (-10^18). To know how many were sold, you can divide by 10^18 or simply truncate the last 18 digits: 557303 tokens (and some RKCents) sold as of this moment.

1000 ETH will coming, hopefully all tokens sold out