A lot of pro-immigration people quote that figure about illegal immigrants paying taxes, as though paying even a single dollar in tax represents a new benefit to government finances. However, the government needs to collect more tax than they spend for an immigrant to be a net benefit.

The $11bn in tax revenue works out at around $600 / capita per year (there are around 17 million people living in illegal immigrant headed households).

For reference, the (limited) welfare state in the US spends around $3,000 / capita and total government spending is around $17,000 per capita.