Is this character in True Detective a reference to a real life photographer?

You're not the first person to discover the significance. According to this review, the reviewer correlates Dora to Dorothea and points out she is the "portraitist of the rural downtrodden". Dora, in that series, was a prostitute; a rural downtrodden.

I don't know that Pizzalotto would address the correlation explicitly, given that he's also never addressed the allegations of plagiarism of Thomas Ligotti's writing, which has been pointed out multiple times by interviewers and critics. I couldn't find any interviews where anyone specifically asked him that question.

Is this character in True Detective a reference to a real life photographer ?

_{In True Detective season 1, the murdered woman whose case Rust and Marty take on in 1995 is called Dora Lange, a name remarkably similar / practically identical to the real life great Depression-era photographer, Dorothea Lange.}

Doubtful.

Basically, the True Detective's first season has two main sources of inspiration:

• Robert William Chambers' 1895 anthology The King in Yellow, mentioning Carcosa, a name occurring in Ambrose Bierce's 1886 short story An Inhabitant of Carcosa, and later borrowed by H. P. Lovecraft for his Cthulhu Mythos; both terms feature preeminently in Dora Kelly Lange's diary, as can be glimpsed from the season's second episode.

• The 2005 satanic ritual abuse case against pastor Louis Lamonica Jr. of Hosanna Church, in Ponchatoula, Tangipahoa Parish, Louisiana, as intimated by the series' own creator, Nic Pizzolatto, in a 2014 interview for Entertainment Weekly, and explicitly mentioned in a follow-up later that same year, with Buzz Feed; one of the defendants bore the same surname as the show's other victim, Fontenot.

Throughout the whole series, the first victim's surname is pronounced Lang, with a hard g instead of a soft one; furthermore, in the third season premiere, a copy of the fictional book The Forests of Leng is seen in the missing child's room; when taken in conjunction with one another, especially in light of the information presented at the first bullet point above, this points towards Lovecraft's Plateau of Leng, mentioned in eight of his Dream Cycle writings, penned throughout the 1920's and early `30's; this is further strengthened by the lyrics to the show's opening credits, mentioning a plateau-like landform, called mesa.