If you are not married your support is irrelevant. There is no minimum income requirement so if she can show she works remotely, even with a modest income, she should be OK but will of course also need the 500k baht or equivalent in her bank as well. If she will work remotely from inside Thailand soft power is not appropriate, she'll need to stick with workation.
If your friend was denied entry last month trying to enter from a nearby country is likely to end up with the same result. Thai immigration systems are all linked