it mostly depends how many disabled,old ppl or orphans are there in China
but
1) disabled ppl or old ppl may still have jobs or pensions
2) if they don't have jobs or enough pensions, they have government allowances, rural poor ppl get $30/month while city ppl get $60/month, and this allowance continues to grow
so the ppl under that lines are :
1) a few disabled/old/orphan ppl who have no jobs and don't know government policies (e.g, they have no relatives/friends who told them and a few local governments havn't done a responsible job to include them in)
2) some isolated areas where the ppl are lazy, religious and are not willing to work in the cities and enjoying the primary-style life
I don't how many of them, but it is never as many as 80 million