I recommend the geneticist Razhib Khan as someone conservatives usually trust. He states he is convinced she is something between 1/64th and 1/1024th Native American. That may not sound like a lot, and it certainly shouldn't qualify her as an affirmative action hire nor make her tales of her mother being discriminated against, but it is legit. Many of the criticisms from the right have been leaping to conclusions and getting the science wrong.
Let me re-emphasize that. A lot of conservative sites are getting the science wrong, in their eagerness to discredit the finding. Make sure you know what you are talking about before you pass on any debunkings of Warren.
No tests can identify tribe at present, but this would be consistent with what the New England Genealogical Society* found, of a partial Cherokee ancestor five generations ago. How partial is unknown. If you are interested if this means that Trump is obligated to pay her a million dollars, retired law prof Ann Althouse discusses this and concludes "probably not," though she thinks it would all be very entertaining if EW sued for it.
*This was subsequent to Warren's public claim.