1) Yes, the i7-860 will bottleneck many games.
2) GTX1050Ti is still a great choice to upgrade that system.
3) Upgrading anything else unless minor makes little sense. The CPU is also about the best for that SOCKET.
4) Be careful choosing games that your CPU is sufficient. Dayz and PUBG may not be good choices due to the requirements (in big part due to optimization).
5) i7-860 performance:
https://www.cpubenchmark.net/cpu.php?cpu=Intel+Core+i7-860+%40+2.80GHz&id=6
- per core lower than an FX-4300 (1407)
- *Best choices is older games, less demanding games, or possibly some MODERN games that can utilize enough of the eight threads to perform acceptably
6) "Can I Play It" is okay rough guide
- other rule-of-thumb is make sure CPU is above minimum recommendation by more than a small amount
- can look at benchmarks using the FX-6300 then assume your FPS could be only 70% or so. hard to guess exactly.