Hey! So I did some testing and it appears that a player will load in 8 chunks in front of them when looking forward. However, if you are wanting to load in spawners for them to work, spawners will only activate if a player is within 16 blocks of them in any direction.
I hope this answers your question, if not feel free to respond or ask me in game anytime and I'd be happy to try and get an answer to you.
Best,
TeamJacob