On one website I looked at, it benchmarked the GTX 1050 Ti at 83 FPS on GTA V, so getting below 60 does seem to be unusual.
One thing that stands out to me in your system, is your Pentium processor. It's more a low-medium range processor, that could possibly be bottlenecking your graphics card.
First thing, is to make sure your computer is on the high performance setting in power options in control panel.
There also could be viruses or programs eating up your systems resources that give you a lower FPS in games. There's a couple ways of monitoring this.
The first step would be to pull out Task Manager while the game is open, and see where your CPU usage is at. Make sure to click the CPU usage tab, and see which programs are taking the most CPU resources. If the only program taking more than 5-10% of your CPU is the video game, then we can figure that there aren't any programs hogging your computer's resources. If this is the case, and your CPU usage is at 95-100% solely from the game, then this is a good indicator that your CPU is bottlenecking your graphics card.
While you have Task Manager open, look at the RAM usage as well. It shouldn't be much higher than 80% usage while your game is up.
Next step would be to download GPU-Z here: https://www.techpowerup.com/gpuz/
While in game, pull that out and go to the monitor section in GPU-Z. See if the GPU usage is at 95-100%, if not, there this might be an issue of the CPU bottlenecking or an issue with the graphics card. If it's not at 95-100% usage, check the voltage and wattage monitors in GPU-Z as well, and note those.
The only other option I can think of, to make sure the computer is performing where it should, would be downloading a benchmark software like
PerformanceTest by Passmark. If you do the benchmark, make sure to upload it to their website (one of the options in that program) and give us the link.
Hope this helps.