There are perhaps 15-20 million East Pakistan/Bangladeshi origin Hindus in India due to legacy of partition. But this number is less than the number of Hindu/Shikh forced to migrate to India from current Pakistan. In 1947, 7 million Hindu/Shikh were driven out to India(similar number Muslims were were also forced driven to Pakistan). Since 1947, Indian population is multiplied by 4.5 times. So if you apply the same multiplication for those 7 million who were driven out from Pakistan then there are at least 30 million Pakistan origin refugees and their descendant who are now in India. But that was a big, one time affair. Hindu/Shikh in Pakistan and Muslims in Indian Punjab, Haryana are almost cleansed in 1947 . No possibility of migration in later times. So nobody is bothered about that right now.
But Hindu migration from Bangladesh did not happened much during 1947, but it continues to trickle into India at steady flow in low intensity year after year. That is the problem and lead to a lot of confusion and misjudgement in India. Assam's current turbulence is lot due to thus nature of partition legacy migration. Hindus continue to trickle into India even after 1971 due to various reasons. What they are screaming about Bangladeshi migration are largely about this Hindu migration, but Indians have a misleading idea that a lot of Bangladeshi muslims are also migrating to India. Which is totally blown our of proportion. If properly varified, I think Bangladeshi Muslims working in India would not come close even to a million, less than the number of Indians currently working in Bangladesh. So, Indians need to separate this two type of migration, but they jumbled all type of migration of Hindus and Muslims from Bangladesh both for reasons of partition and working opportunities into a big Bangladeshi migration invasion narratives. This is simply not true.