There actually isn't any data accepted in the *scientific community* that proves second-hand smoke kills. There are a few widely known studies that present it as a possibility (hence laws banning smoking... and health conscious yuppies taking a stand against it), but many other studies (albeit haven't gotten much attention for political reasons) that STRONGLY suggest (and, if wider studies were done with the same results, prove) it has little or no effect.
Also, even for actual smokers... 50-60% of smokers die from smoking related illness (keep in mind, "related" is nebulous and doesn't factor in other causes - sedentary lifestyle, socioeconomics [note: lower class is more likely to smoke, but also less likely to have access to good health care, eat "properly", etc...] etc... and makes assumptions based on what smoking *may* cause, and assumes all smokers get that BECAUSE they smoke, not taking into account people who never smoke/aren't around people who smoke and get the same - ie: a smoker who dies of cardiovascular disease is counted as a "smoking death", but a non-smoker who dies of the same is counted as "natural causes"), but less than 10% die before the age of 75 of those smoking related illnesses. ALSO note that lung cancer (an asthma, etc...) in America has dramatically increased in the past half century, at the same time smoking has decreased by half. Most scientific studies suggest there are many other environmental factors and smoking is a smallest contributor.
Smoking's not good for you, but it's not as bad as anti-tobacco lobbyists have people believe, especially second-hand. Eating fast food once a week or more is shown to cause more health problems than smoking.
Will the dog die of cancer? Maybe. Will it be related to the man smoking cigarettes? Not likely, but it's possible. However, if he does, it will likely be when he's to the age a dog would be expected to die anyway. There's a certain age when your body just shuts down and *something* will catch up with you.