You can already kill someone by throwing a smoke grenade at someone, that's pretty well documented. I'm going to assume you mean smoke poisoning.
In that case, the titanium tetrachloride mixed with the calcium chloride solution should (I believe) only cause redness of the skin, dry skin, a cough and a sore throat for short durations of inhalation and exposure. And that's probably worse case and unlikely. In this reaction, the calcium chloride merely facilitates the production of smoke by hydrolosis of the titanium tetrachloride. So, not very harmful. In that case, maybe 2-4 damage is appropriate for every 10 seconds in the smoke.
But on second glance, I noticed the grenade here (on the right) is the Blendkorper 2 H. This is, in fact, not the smoke grenade used in DoD:S. I believe the game uses, instead, the Nebelkerze 39 (noted for its cylindrical chassis) which involves an hydrocarbon-zinc mixture and whose toxicity level I honestly don't know. Chemists?
Fun Fact: The smoke would appear immediately after the pin was pulled on the NB39, kinda wish it would do that in the game so I could run around after the pin pulled like some idiot on fire.