Renault publish sales figures but only back to 2007.
Automobiles Review concur with Top Gear, stating that, in July 1984:
Commercial launch in France with only nine sales in first month and 2,427 sold in the year.
While they don't cite sources, note the additional full year figure, which suggests they did not source this information from Top Gear themselves.
Also notice that the Espace was not launched in the UK until July 1985, so when Hammond says "racked up worldwide sales... of nine", it is strictly true, but was really limited to the French market.
Aside: I know little about the sales and distribution channels of Renault in 1984, but with the products I have been involved with, I note that there was often a gradual roll-out (rather than a giant flashy launch), as the new distribution and retail processes get set-up and the gremlins sorted out. In such cases, there initial roll-out can be deliberately limited, and a small first month is not seen as a failure, but as planned. Once it has been established that orders can be fulfilled correctly, the marketing effort can begin in earnest.