In a post by director of game operations Jeremy Masker, it was confirmed the game's size and number of assets mean its client will be sizeable. Likewise, he says, patches for the game are also expected to be on the larger-side.
The size and number of assets that are left to deliver means that our client size is much more likely to be 100 GB," wrote Masker. "We are optimising game patching for speed and to only deliver diffs, but this is unlikely to reduce actual patch size. Again, each patch has 100s of assets, each of these assets are at times 200mb, this leads to 2-6 GB patches, and if we end up doing a file type re-factor and have to re-download 30-40 per cent of the assets on the hard-drive, then the patch will be 14-20 GB."
Star Citizen is still looking at a full commercial launch in 2016, with beta rollouts of components such as its FPS module between now and then. The game has surpassed $70 million in crowdfunding since it began taking donations in 2012, and expects to top $100 million in crowdfunding before it's all over.
For more, see Polygon's preview of an early access build of the space combat MMO from earlier this year.