of course it can be taxed, if a citizen that use bitcoin want to declare his revenue from it, it will be taxed like any other fiat money
taxing directly bitcoin is a bit more difficult for the government if their citizenz are not willing to help by declaring their income per year
And who wants to pay taxes and go directly to the pocket of corrupt government ? bitcoin can be really taxable and they can mandate its people to declare their income simply because the technology of bitcoin that makes it more unique, I think government should support everyone because it can boost the economy.