These anti-amtrak senetors must be bribed by the airlines and auto manufactures who want people to use more gas and fly more.
Not really. Amtrak only carries 31 million passengers a year. The airlines carry over 700 million, and the bus lines over 800 million. I don't even know how much it is for cars, but I know automobiles make over 90% of all intercity travel. Cutting Amtrak entirely wouldn't affect the competitors much.
This does comes to backfire against Amtrak because this means that many people would honestly (no bribery) argue that Amtrak is a "nearly useless and non-vital transport service only used by a small fraction of the population for transport and otherwise for land-cruises or railfan obsessions".