Selecting an NTC for inrush current limiting
Possibly; this page from Ametherm has a lot of description and guidance on how to select one. However, the cases they describe are mostly power supplies, where the inrush current is into a capacitor, and the NTC heats up and passes full current pretty quickly.

Given that you're building a triac control circuit, I suggest looking at "triac dimmer" circuits and using one of those instead. You can then control current either by "dead reckoning" (gradually increase power over a time period that gives the desired result) or by measuring current flow (eg Hall sensor or current transformer).

You also need to consider what happens if the heater fails short-circuit. The triac needs to survive until the fuse blows or circuit breaker trips.

It may be simplest to just overbuild the triac to handle the inrush current.