So every single time I tried to get online, I'd get right up just prior to the initial race thing starting and it would always hang on "Finding other players" -- literally tried it again and again like 9 different times.
In a dark, foul and increasingly frustrated mood, I sought solace via our good friend The Google and discovered the cure-all fix for this particular problem (note this only works for Xbox 360, to the best of my knowledge):
1. Quit to your dashboard.
2. Go to settings.
3. Go to storage settings.
4. With your main HDD/flash drive that has GTAV/GTA: Online installed highlighted, press Y.
5. Clear system cache.
6. Reboot, launch the game and try to get online again.
7. Weep unabashed, manly tears of joy as you realize this actually fixed the problem.
My son is out of his mind trying to get on. I showed him the above and he is worried this erase his game play status. Seems like this wouldn't be the case, but wanted to check. Thanks!
The only semi-important thing that clearing your system cache removes are some game updates. And this is usually only for older games. These can easily (and oftentimes will automatically) be re-downloaded whenever you launch the game and are connected to Live. Thankfully, clearing your 360 system cache
won't affect the GTA5/GTA: Online game updates, so no worries on that front if that would also be a point of worry.
Clearing your system cache essentially just clears up and deletes temporary game and system files that have become damaged and are more or less useless. Say, when you create 2-3 separate save files for one game and end up deleting one or two of them (to cut back on space). Those game saves that you delete will -- for whatever reason -- leave behind a relatively minuscule imprint of themselves on the hard drive. Think along the lines of clearing the temporary files/history of your Internet browser -- especially in that, say, it won't delete your bookmarks but will instead just help clear up the unnecessary junk and keep everything running smoothly/not be overloaded with tons of needlessly excessive files/data.
Microsoft actually recommends clearing your system cache at least once or twice a month (it really depends on how many games and/or how much you play) to help ensure things are running smoothly from a system perspective. It definitely doesn't affect game saves or dashboard apps in any way, shape or form, though. I can promise you that and give you my word!