This site gives current populations, although in keeping with apparent Bureau of Indian Affairs Policy, it is practically indecipherable: http://www.doi.gov/bia/ifcons95.html
As for aboriginal population, dickshovel (yes, I know…) says:
European epidemics introduced into the southeastern United States in 1540 by the Desoto expedition are estimated to have killed at least 75% of the original native population. How much the Cherokee suffered from this disaster in unknown, but their population in 1674 was about 50,000. A series of smallpox epidemics (1729, 1738, and 1753) cut this in half, and it remained fairly stable at about 25,000 until their removal to Oklahoma during the 1830s. The American Civil War was the next disaster and cost the Cherokee 25% of their population. No other group of Americans, red or white, suffered as severely during this conflict. The 1990 census listed 308,132 persons (15,000 full-blood) who identified themselves as Cherokee. Of these, 95,435 were concentrated in eastern Oklahoma while 10,114 eastern Cherokee lived on or near the North Carolina reservation. Cherokee tribal governments have fairly liberal membership standards, and some estimates exceed 370,000, which would make the Cherokee the largest Native American group in the United States.
The cite is http://www.dickshovel.com/Cherokee1.html . This is one of the finest clearinghouses of Native American history, despite its odd name.