When a crowded police chase starts, surviving is mostly about staying calm and protecting your speed. Pick a vehicle you can control at high speed, keep enough room to change lanes, and avoid committing to narrow streets until you know where the pursuing units are coming from.
Use the city layout to break line of sight rather than driving in a straight line. Turn through areas with several exits, vary your route after each turn, and save repair stops or hiding spots for moments when the police group has spread out. A quick route change is usually safer than trying to force through a roadblock.
If you are outnumbered, focus on escaping instead of winning every encounter. Watch the minimap, communicate with teammates when you have them, and reset your plan after each close call. Clean driving, patient timing, and a prepared getaway route give you the best chance to stay in the chase.