Top 10% of Bengalis have 35% of the income, in a country with a purchasing-power parity (PPP) income per capita of $1909. So my guess would be top decile makes about $6-7k/year. This is in a country with zero public services (while someone living on $10k/year in the U.S. has access to public education,* public housing, food stamps, Medicaid, etc). India is substantially better, but at around double the PPP income of Bangladesh, that puts top 10% of Indians probably right around the bottom 10% of Americans.
*) American school spend on average $10k/year per student.
Monthly salaries are about $15-$30. No, I'm not forgetting a zero.
They get free education and health care (though quality of the latter varies) and they get a few cheap food as rations.
There are a few other benefits, but in large part they're quite poor.