Strong longtermism states that when making a decision, we should primarily consider its long-term effects.
From this perspective, the argument that one should not eat meat because it causes more animals to be farmed is weaker since the (relatively) short-term effect of an additional animal being farmed is dwarfed by the long-term effects of eating animals.
Are there any fleshed-out, longtermist arguments out there on why people shouldn’t eat meat?
Also, I would be interested to know how the damage done by eating meat compares to the positive impact of donating money. Having such a comparison would allow us to price the damage done by eating meat.