In favor of the theory of Galatians 2:1-10 referring to the Acts 11 visit are the following:
- This visit clearly is prompted by a revelation by the Holy Spirit.
- The Acts 15 gathering seems to be a public gathering, where the one described in Galatians is private.
- Paul never alludes to a letter sent to the diaspora churches which could have definitively won the case for him.
- The issue of food laws was already decided by James. Why would men coming from him in Galatians 2:11-14 be advocating a view stricter than the already existing agreement?
- Paul only mentions two visits to Jerusalem. If he visited 3 times why does he omit the visit in Acts 11?
- According to Acts 15, false teachers requiring circumcision had already been to Antioch.
- Why would Paul be told to remember the poor if he had just dropped off a pile of money for famine relief?
- The issue of Gentile circumcision is central in Acts 15 while it never comes up in Acts 11.
- There is mention of false teachers who demanded circumcision of Gentiles in Acts 15.
This brings up the question of dating. Many scholars opt for an early date on the basis of seeing congruence between Acts 11 (which we can probably date to 48 CE) and Galatians 2. However, I think a later date is more likely on a couple of grounds. First, I would argue that Acts 15 happens 17 years after Paul's conversion, which would put it somewhere in the vicinity of 50-52 CE. Then we need time from there for the events of Galatians 2:11-14 to happen and then for the false teachers to make it to Galatia and for Paul to write the letter. So that would probably put us in the mid 50's. Second, in terms of content, Galatians fits in nicely with 2 Corinthians and Romans, both of which are dated somewhere around 55-57 CE, so it would seem like Galatians would fit well somewhere into that date range.