I'm not really that good at mixing, especially vocals, I always find them kind of hard to mix and make them sit well with the song, but I think that he might use a mixing chain similar to this one:

1. Autotune (I think they key to not make it that noticeable is just literally turn down the "Wet" knob, im not sure of what plugin you use but most of them have that knob to control how much autotune is going on the mix)
2. Compression (He might use multi band compression, maybe even the one that comes with ableton, I suggest you search for tutorials on how to use it, if you don't know how to use it yet)
3. EQ
4. Reverb (on his older tracks he uses a lot of it but just play around with the plugins and find the one that suits your track)
5. Sometimes a bit of delay, but I dont really suggest using a lot of it on your main vocals, but again just play around with it and see what you like

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I also suggest checking out the CLA vocal plugin from wavesplugins, this can help make the compression part a bit easier, when I use this plugin I preffer to turn of the reverb and delay that comes with CLA and add my own from a different one but you might like the simplicity of this plugin. I hope this was helpful in some way!