No. If your annual income as reported on your taxes is below the income cut off for Medicaid eligibility, you do not have to pay back the premium tax credits you received.
For example, if you projected your income to be 140 percent of the federal poverty level, but your annual income is actually 130 percent of the federal poverty level (making you eligible for Medicaid in most states), you do not have to pay back the premium tax credit you received. In fact, your final credit amount will likely be larger than the amount you received in advance. Note that if you end up making more than you projected on your application, and were not eligible for the amount of premium tax credits you received, you may have to pay back a portion of those tax credits.