The chances are better with a small, fresh chip without long legs and without ingrained dirt. Size, depth and position are assessed on inspection — a photo only allows a preliminary answer.
When the crack is long or complex, several layers are damaged, there are many defects, or the glass can no longer be restored safely.
Not always. The purpose of the repair is to fill the damage and stop the crack from spreading. The defect usually becomes noticeably smaller, but an optical trace may remain.
Moisture and dirt get into the damage, while temperature swings and vibration extend the crack. The sooner the repair is done, the better the chance of saving the glass.
A repair restores glass that is already damaged. Protective film is applied in advance and takes the stone impacts — these are different jobs.