Nader Habibi reviews the evidence and concludes that the funds that would be made available to Iran in the near term as a result of sanctions relief is not very great:

Kamyab and several other Rouhani government officials have argued in recent weeks that only the first and second items in the table are likely to be available for use in the short run as a result of the nuclear deal.

These items add up to just $29 billion. The rest may remain blocked for much longer because of legal disputes and ongoing tensions between Iran and the United States over other issues.

Habibi notes that this amount is approximately half of Iran’s current oil revenue, so sanctions relief is not going to provide Iran with that much extra funding. Out of this relatively small amount, some fraction of it might be used to support its allies and proxies in the region, but this wouldn’t have much of an effect in any of these other countries and it would continue to be dwarfed by the much higher military spending of Iran’s regional rivals. Sanctions relief isn’t going to fuel Iranian regional dominance or anything like it, and opponents of the deal that keep repeating this claim as one of their objections to the deal are peddling falsehoods to try to frighten the public to take their side.