My 6 year old has been having headaches for 6 weeks.i have taken her to an eye dr and she is far sighted.im worried about brain tumor.is this likely?

No: Rare things rarely happen. Does she throw up in the early morning. (sign of extra brain pressure) ? Are there other physical symptoms or deficits of function ? Headaches do happen in kids for a lot of reasons but vision issues & brain tumors are rarely the cause. I would start with an evaluation by her regular doc to find a real cause and solutions.