The amount of money needed to fund the ongoing operations or future development of a business or project that is not currently provided by cash, equity or debt. Funding gaps can be covered by investment from venture capital or angel investors, equity sales, or through debt offerings and bank loans.
Most often used in context with early-stage companies during the initial stages of research, product development and marketing.
Taobiz explains Funding Gap
The ease with which a very young company receives funding depends on many factors including the viability of the business model, barriers to entry for that particular industry, and overall economic and market conditions. When the stock markets are strong, venture capital investors are much more likely to fund startup companies, and may even become less stringent in their eligibility criteria.
Funding gaps are also more likely at these early stages because a company won't know what its full operating expenses will be until it reaches a more mature stage and, at first, there aren't likely to be any meaningful revenues coming in.