Since you sent on November 12th which fell on a weekend, the letter would have gone out the following Monday. From that point the postal transit to the facility runs about 2 to 3 business days, putting arrival at the facility mailroom around Wednesday or Thursday of that week.
What happens after the letter arrives at the facility depends on the specific protocols for death row mail. Death row housing operates under stricter controls than general population in virtually every state system, and mail handling reflects that. Every piece of incoming mail gets inspected before distribution, and death row mail often goes through additional review given the heightened security classification. That inspection process can add a day or two beyond what standard population mail requires.
Death row inmates do receive mail and it is one of the more meaningful connections available to them given how restricted their daily lives are. The letter will reach him, though the exact day it lands in his hands depends on how the facility schedules mail distribution for that unit.
Based on the timeline, he should have it within the week of sending assuming no unusual delays in the mailroom. If you have not heard any acknowledgment after two weeks, reach out to InmateAid's support team. If the letter was returned for any reason it comes back to InmateAid's Florida address and they will investigate and resend at no charge.