Depends on the filter. If you have 1" filters and substitute the cheap fiberglass ones that you change ever month, with a 1" 3M filtrete, you'll increase the resistance to return air flow. This might not be good for your older system. If you have 4" filter, however, you can go up to MERV 13 no problem.

Better solution - No Smoking In The House!!!

Upgrading in the conventional sense would help odor tremendously but upgrading to specialty filtration system such as charcoal could help a lot. Kicking smokers outside works better than anything else.

I use 1" Glasfloss ZL Merv 10 filters which you can order from Walmart or AirFiltersUnlimited, among others. Unit prices often vary a lot with quantity. I understand you should not use a high MERV filter on an older HVAC unit -- because of reduced air flow -- and the suggested MERV 10 won't remove tobacco smoke.

Tobacco smoke has two separate but related filtration challenges--particulates (which make the smoke visible) and volatile components (which produce the odor.) Since the smoking is confined to a single room, one option is to decouple the room from the central HVAC system and stop spreading smoke and odor throughout the home. You can install a mini-spilt heat pump dedicated to the room and a smoke and odor filtration system in the room (there are portable and fixed options available.) The other is to install a smoke and odor filtration as part of your central system. If your home has a porch, making it a more comfortable year 'round space for smoking is what I'd opt for.

A hypothetical question for X-smokers. What amount of money would it take in exchange for smoking one pack of cigarettes,payable when you finish the last one but take all the time you need?

If I understand your question, are you asking "How much would it take to get you to smoke a pack again, after quitting"?

If I have that right, I wouldn't do it for any amount of money. Not even $1 million to smoke one. I quit decades ago and regret I ever took up the habit.

Thank you everyone for responding on this issue. I think we may look in to other options such as a good quality room air purifier and continue to encourage the outdoor smoking which works 50% of the time.

CR tested air filters. You didn't specify the thickness you needed. Among 1" thick filters, the Filtrete MPR 1900 earned a "recommended" rating, 5/5 for "Dust, pollen, smoke removal" at high blower speed, and a 4/5 for airflow resistance so you might try one of those, not the Filtrete MPR 1900 Smart which did worse.

Filtere MPR 1900 filters can be had for $25 at LOwes. You could make lots of money selling odor removal service through realestate brokers buying filters for $25 each and charging 1% of sales price to remove smoke oder from homes.

While mechanical filtration is capable of removing particulates, it won't do much, if anything, for odors. To capture odors, you'd need activated carbon on which odor-causing chemicals are adsorbed.

Quitting smoking was one of the hardest things I’ve ever done and it took multiple attempts over several years.
Try alan carr easy way to quit smoking and read it several times. It might help, it can’t hurt. Smoking sucks.