Yes they are, but they'll be integrated. The logistical problem with the 300 baht was collection. The airlines don't want to do it, and it would be impossible to segregate tourists from non-immigrant entries. Collection at immigration would only add further to the queues and congestion at busy times. Some bright spark suggested the ETA (which was announced back in March) would provide the opportunity to levy the charge on tourists, as only visa exempt entries will be subject to the ETA
Not quite. The tourism tax was delayed because the government didn't know how to determine tourist entries from longstay visa holders. The ETA allows for this, as payment will be made when application for the ETA is completed online. It'll be through the Thai visa website. They've delayed it because priority is being given to the remaining countries to get into eVisa