On J1 you are a nonresident alien for the first two (as nonstudent) or five (as student) calendar years. After that, you use the substantial presence test to determine residency.
The tax treaty does not make you a nonresident alien for tax purposes, but would allow you to claim a treaty exemption if it has an exemption to the savings clause.
If you meet the SPT, you are also required to file the FBAR form.
