Don't close your outfit.
The best option you have is to outsource your expertise and downstream, outsource to other developers with agreements that can benefit all concerned. It is not always that the piece of work needs to be paid for in full as would be the case, the main client will put up funds at given milestones and you can also do the same to the team that will be supporting you.
It appears that your benefactor has seen your future prospects and earning a wage on that is not really the best approach. I would think that developing your software portfolio and either selling it as a service to his company (partnership) also allowing you to source your own market would be the best bet.
As you have stated, capital resources are hard to come by, people and hard cash, but if you take time and develop that network, I believe you would be hitting those numbers he must have mentioned to you.
What of if getting on-board with the company is the only alternative? Well just make sure that you gain a good reward for the portfolio you already have, put down what the going concern price you are happy to work with, and since these are your "babies", you would also need to see how they will fit in the bigger scheme of things. For this I mean, if they need to be developed further, then the partner/employer is happy to start talking funding numbers for
these, if they will be cannibalized and left for dead, that will hurt you more than you might think.
One crucial point to keep in mind also is the environment you will find yourself in. Are there like minded people in there? It's all well and good moving in, but are there the techies that will complement your knowledge/expertise or better still people who you will be happy to work with. Will you be swamped with the current and future developments that the company is working on/towards, or are you to develop a line of tools for the company?
All in all this experience must have emphasized your strengths and shown you what might be achieved with a bit more effort in networking and marketing, if for whatever reason you decide to remain a sole operator, what "mikakati" have you set yourself...
All the best and hope you do make the right decision for you in the long run...
KK