The image doesn't give us enough information...not even for any 'wild guesses', lol. Perhaps some close-up shots of the leaves, stems, etc.

How many hours of sun does it get and from when until when? How do you water it? How often? How much? Do you fertilize? If so, what do you use and on what months do you fertilize? Have you done a soil test before to see the pH of the soil and nitrogen levels? Stuff like that? How long has it looked like that? Can you guess as to when it started looking like that?

What is the planting depth? A common cause of camellia failures of otherwise healthy plants, is planting depth. It's very easy to dig and hole and put the plant in and cover it with a foot of soil.

I also see it's on a mound. Check the plant with a moisture meter to see if the root-mass is getting water, or if it's running off.

I also agree with Luis PR - get the soil tested.