The amount of money you can send, as well as the frequency, is set by each participating financial institution. The SoFi send baseline limits are detailed in the Zelle® Network Standard Terms. Limits are periodically evaluated and may be automatically adjusted based on historical usage.
At SoFi, there are currently no limits to the amount of money you can receive with Zelle®. However, remember that the person sending you money will most likely have limits set by their own financial institution on the amount of money they can send you.