> someone explain how congestion pricing helps the MTA money problem

The legislation passed by the New York State Legislature mandates that the CBD tolling (congestion pricing) raise $1 billion per year that must go to the MTA's Capital Budget. The Capital Budget is what funds projects and construction, such as this proposed extension.

> Other than the net positive of reducing emissions, which could be achieved in a 1000 other ways

I think you are vastly underestimating the solutions available. Do you believe the city has unlimited money to convert private resident's vehicles into electric vehicles to address emissions? Also, one of the two primary goals of CBD Tolling is reduce congestion, which cannot be done easily either. You need an incentive to get people to not want to drive into the city. Either you make it physically impossible or harder to drive in (which will receive complaining and bitching, of course), or you enact a real cost to reduce trips into the CBD. The multi-year long Environmental Assessment analyzing CBD tolling was based on several goals, I cannot remember the exact numbers but I think it was around a 10% to 15% reduction in vehicles and vehicle-miles-traveled (VMT) inside the CBD cordon zone, which are arguably real, quantifiable, net positives for the CBD. Hope that helps a little.