The Short Version #
Reliable primary documentation and independent news reporting confirm that OpenAI released GPT-4 in March 2023. Most sources identify March 14 as the announcement and initial rollout date; reporting dated March 15 reflects publication timing or the continuing rollout, not a substantive contradiction.
source & further reading
isthisbs.org — original article
GPT-4 launched with 8,192 tokens and a limited 32,768-token variant.
ChatGPT reached an estimated 100 million monthly users in two months.
ChatGPT had an estimated 100 million monthly active users by January 2023.