Basic economics says that as we increase the supply of something the price goes down, so even if this doesn't get EVs to a price where everyone can afford them it gets them to a point where more people can afford them.

Gas tax is a consumption tax, which is inherently regressive. This means that it costs more for lower earners as a proportion of their income. If a low wage earner wants an EV they can't currently afford one. A gas tax punishes them for this financially and makes it less likely they will be able to save for an EV. Meanwhile higher earners that can afford EVs don't pay the gas tax because they don't buy EVs.