Can a frontal lobe tumor make someone psychotic

To put it simply... Yes. The Frontal lobe controls that basic emotions and thought process, that make you, You. A tumor would definitely interfere with those processes, and you can end up with patients with some form of AMS (altered mental status). They could end up with a biological psychosis, hallucinations, depression and anxiety, Anasecoria (uneven papillary dilation, due to pressure on the optic nerve), Delirium, or Dementia.