How can you find out who is a beneficiary and the share entitled to in a living trust?

That's a difficult situation. You would need to ask the grantor of the trust if you can review a copy of their trust. It is a private document and they may not want to share it with you. If you think you are a beneficiary and are not receiving income you may be able to petition a court of equity to examine the trust document. If you are very serious about wanting to know more you should consult with an attorney.