The total supply of LEO tokens is currently just over 5 million, with a max supply of 1 billion.

This is shown on the right hand side of the current LeoFinance interface, as seen on the screenshot below.

On that table you can also see that over 4 million of the circulating supply of LEO tokens is currently staked, limiting available liquidity on the open market.

As for whether the total supply of LEO tokens can be extended, the answer is no. Supply is fixed and can't be extended.

However, as @taskmaster4450le said in the comments, the reward pool is spitting LEO out on a consistent basis within these supply confines. Something that will continue, with an ever decreasing inflation rate toward the token supply limit.