can you please tell me if he can obtain a Visa for this as i can not find an answer on all the sites

Yes, he can visit China as long as he has a Chinese visa.

Thanks for that, I know that he can enter with a visa, i have a problem with the criteria for this, on the web site they request some proof of an exit date from the country via an airline ticket etc, unfortunately my son will only have a one way ticket to china as the rest of his journey will be on foot,, my question is," will the authorities issue one on his travel itinerary as they do not cover this aspect on their web site". thank you

Hi, I think a detailed itinerary to travel south east asia and hotel bookings are helpful for application. He can also explain to the officers that he will visit by land without ticket booked before leaving.