I am 7 weeks and 2 days pregnant and i took the multivitamins + minerals. can i still take folic acid 400 gms?

Yes: I am sure you mean folic acid 400 mcg. Hopefully your multivitamin already contains folic acid, as it is most important the first few weeks of pregnancy, but there is no harm and potential benefit to taking larger amounts. About one third of people have difficulty converting folic acid to L-5-methyltetrahydrofolate (L-5-MTHF), the active form, so it is wise to take the L-5-MTHF form.