A very slight chance it might have caused a bad run of tachycardia which then went into v fib, which then went into asystole (cardiac arrest). Caffeine does cause an increase in heart rate and can lead to tachycardia if the dose is too big, that can happen even in healthy hearts.
His heart was not healthy, autopsy showed it was enlarged, and he probably had what doctors would call cardiomyopathy. Ejection fraction was probably compromised. Hearts in this condition can get out of rhythm easier. Right now I have to avoid taking in a lot of caffeine or I will have rhythm problems.
It is probably unlikely, but there could be a link. Did reports ever say he experienced cardiac arrest? I think they did.
Dr. Thomas O'Connor made a video on youtube called "Rich Piana *Autopsy RELEASED* - Enlarged Heart" where he gives his opinion on what he thinks happened.