As I said, the very wealthy and the corporations can pay more in taxes, a lot more. However, I do not see them providing near enough to fund the Sanders Plans. One example of where corporations can do more is to collect sales taxes on online and mailorder purchases. Currently these are pretty much exempt by US law.
While the purchaser would ultimately pay the taxes, it would level the playing field for the many retail businesses that are facing bankruptcy or closure.
I buy from Amazon all the time, and over the past 6 months they've been implementing sales tax charges, which fluctuate depending on the state where the item is sold or shipped from. I now pay sales taxes on approx. 75% of all purchases on Amazon.