"Low income" is a matter of opinion.
And your question is vague, too. In states that allow Medicaid for families (ie, non-disabled adults, as well as children), then $9500 a year income for three people will qualify for Medicaid in just about every state.
Those families would ALSO be exempt from the provision of "obamacare" that requires them to PURCHASE health insurance. However, odds are they'll still be paying TAXES that go towards paying for "obamacare".
Maybe you think that Obamacare is actually an insurance program - it's not. It's a bunch of taxes, and a requirement that you go out and buy health insurance.