Filas are very good with, and can be extremely tolerant of, "their" children. Not ALL Filas are good with children. Some, like in every other breed, are very poor with children.
They are NOT, however, good with other people's children. They will not tolerate your child's playmates, because the Fila sees them as strangers. They will perceive rough-housing as a threat to your child, and will react accordingly to protect his family.
Even the best Fila does not know what is too rough for a small child, nor does a small child know what is too rough for a Fila. They must be supervised at all times.
Just be careful.