No. In New South Wales, gel blasters are considered to be imitation firearms and are treated the same as a real firearm, including registration, licensing and safe keeping regulations. The same maximum penalties for offences also apply to imitation firearms as if it were a real firearm.
Interestingly, the sale and possession of gel blasters is not illegal in Queensland. Therefore, if you lawfully purchase a gel blaster in Queensland or from an Australian online store (which is likely based in Queensland), you must not bring the gel blaster into NSW. If you intend to bring the gel blaster into another state or territory, you should check the laws of that jurisdiction before doing so.