france
Yes, because it changes the charge
Bob's conduct falls under article 221-6 du Code Pénal:
Le fait de causer, dans les conditions et selon les distinctions prévues à l'article 121-3, par maladresse, imprudence, inattention, négligence ou manquement à une obligation de prudence ou de sécurité imposée par la loi ou le règlement, la mort d'autrui constitue un homicide involontaire puni de trois ans d'emprisonnement et de 45 000 euros d'amende.
Causing the death of another under the conditions of article 121-3 by carelessness, imprudence, negligence, or failing to obey a duty of prudence or safety given by the law or local regulation, is involuntary homicide punished by [a maximum of] three years in jail and €45 000 fine.
The theft charge itself and its sentence should not be affected (but that’s likely to be small change compared to the sentence for involuntary homicide anyway).
There is a reference to article 121-3. That article establishes the general principle of mens rea (no crime without the intention to commit it), but it also introduces narrow exceptions that apply here (basically, strict liability for "reckless endangerement"-type charges).
Bob is also civilly liable
He had faulty conduct (committed a crime), others suffered damage (deaths by fire, material damage to the factory), and there is a clear causal link between the two.
Bob’s lawyer might argue to reduce the fraction of damages that Bob is responsible for. After all, the damages only occurred because there was a fire, of which Bob is not responsible. Carol the worker, who started the fire, is responsible at least in part (either as a representative of the company if she acted within her work duties, or personally if she failed to comply with her employer’s safety instructions). Dave the director potentially failed to promptly call the firemen (or establish safety procedures that would have allowed to do so), or skimped on fire retardant materials. If any of those can be criminally charged, there would usually be a joint trial, and the court will decide on a split of responsibility.