In Jainism, it is not possible to say a fixed “how long” you would suffer in hell just from eating meat for 40 years. Karma does not work by a simple calendar rule. The result depends on the intensity of हिंसा, intention, habit, attachment, and other karmas bound to the soul.

A few important Jain points:

• Eating meat causes हिंसा, so it creates bad karma.
• Hellish birth is not automatic for every meat-eater.
• Even if a soul goes to a lower realm, the duration and severity depend on the karmic bondage, not only on the number of years.
• Jainism also teaches that ignorance matters: if a person did not know better, the karmic burden is generally less than deliberate cruelty.

What matters now is:

• True repentance
• Pratikraman
• Stopping हिंसा
• Taking vows toward vegetarian living
• Living with compassion, restraint, and forgiveness

So the Jain answer is: you cannot calculate a fixed hell-term from 40 years of eating meat. What you can do now is reduce future karma and purify the soul through repentance and non-violence.