Ok I'll tell you what I personally think and how I personally play. Everyone seems to do him a little bit different. I agree with Boba that this character is very complex, one of the most in the game, and it's not an empty statement I've learned over half the cast and I'm pretty familiar with what the rest do, Smokes got endless possibilities for creativity in play.
A lot of his depth is in his pressure, which is built off frame traps and spacing traps and input reversing. There is more layers to it than you can imagine, you can just start small and slowly add to your tools tho so don't let it scare you, very basic is 114 forward phase is +4 on block meaning F4 beats every button in the game and hit confirms into full combo so you can force them to respect it. Go from there and build, he has actually endless options with a shitload of his strings and specials, if you want suggestions I can go deeper for you, but you play SG Kotal so you probly know how to work frame data and high/mid mix ups to your advantage
I don't go for the vortex because I feel like his damage is really nice if you don't (~40% for a bar off most key strings and really nice corner game carry), and his neutral is really good so he really doesn't need to try vortex on anyone (except GM Sub lol) he's not like Inferno Scorp, so I just take my damage and my corner and my oki. Personal choice and I'm not saying anyone is wrong for doing it differently, just consider that. Go with what works for you.
Nuetral, I poke with standing 1 string and use D4 as a spacing tool, only ever use D3 when a read of a High to low profile it, I never use D1
F4 is your bread and butter, F13 is sick as well, you should be able to keep your turn after both of them being blocked with smart use of his conditioning off both
B21 is great but do try space it so that B2 connects or they can whiff it by walking forward , now if they armouring this gap (or any other gap that you are worried about) play around with what Phase does for you on this read, its great way of countering a lot armor without necessarily throwing your turn away and leaving you sitting at them blocking on a misread.
F34 I was worried about at first, but after using it, it's like the safest slide in the game. Always delay the second hit, more corner carry that way, and when you do get blocked it's a mix-up - do they wait for your second hit to punish, or are you just gunna hold block? Real cool
Ex phase is great for whiffing shit when you up close, using it defensively when it's your opponents turn or after stuff like a blocked F42 can often whiff stuff and give you full combo just like armor, if you misread it's tricky to punish. For ex phase and just phase in general like pressure phase, remember mixing it up with back phase is your other option making everything your opponent does a risk thanks to the range of B21
Thats basically it, his neutral pretty straight forward other than ExPhase, his depth is in the mix-up/pressure and spacing game, also EX TP is worse than you think in the neutral. Use it sparingly or not at all, he doesn't rely on it like Scorp so should be fine.
If you want BnBs let me know and I'll post mine for you
