How far can a basement toilet be from the main sewer line?

if you are fitting a maserator unit like Saniflo you can go horizontally up to 100 meters or vertically up to 4 meters but you must have a 1 in 200 gravity fall on the horizontal

there is no certain distance it can be from the main. it all depends on the fall and how deep your sewer is, however it does matter how many bends your line has. It shouldn't exceed 135 degrees or 100' without a cleanout.