PTSD is a condition that usualy occurs after exposure to a single traumatic event. C-PTSD (Complex PTSD) is a condition caused by exposure to repeated events that you are unable to escape or avoid so perhaps the better question to ask is - "Is Burnout a Form of C-PTSD?". Although it might seem a nit-pick sometimes it is important to label things correctly to avoid the confusion about 'how can being shouted at by your boss cause PTSD?' vs. 'how can being shouted at repeatedly by your boss cause C-PTSD?'

At this point I would normally quote from the DSM [1] but since they have yet to differentiate between the two conditions (although they will do so shortly) I will instead quote from the ICD [2]

QD85 Burnout:
Problems associated with employment or unemployment:
Description:
Burnout is a syndrome conceptualized as resulting from chronic workplace stress that has not been successfully managed. It is characterised by three dimensions: 1) feelings of energy depletion or exhaustion; 2) increased mental distance from one’s job, or feelings of negativism or cynicism related to one's job; and 3) a sense of ineffectiveness and lack of accomplishment. Burn-out refers specifically to phenomena in the occupational context and should not be applied to describe experiences in other areas of life.

6B40 Post traumatic stress disorder:
Disorders specifically associated with stress:
Description:
Post traumatic stress disorder (PTSD) may develop following exposure to an extremely threatening or horrific event or series of events. It is characterised by all of the following: 1) re-experiencing the traumatic event or events in the present in the form of vivid intrusive memories, flashbacks, or nightmares. Re-experiencing may occur via one or multiple sensory modalities and is typically accompanied by strong or overwhelming emotions, particularly fear or horror, and strong physical sensations; 2) avoidance of thoughts and memories of the event or events, or avoidance of activities, situations, or people reminiscent of the event(s); and 3) persistent perceptions of heightened current threat, for example as indicated by hypervigilance or an enhanced startle reaction to stimuli such as unexpected noises. The symptoms persist for at least several weeks and cause significant impairment in personal, family, social, educational, occupational or other important areas of functioning.

6B41 Complex post traumatic stress disorder:
Disorders specifically associated with stress:
Description:
Complex post traumatic stress disorder (Complex PTSD) is a disorder that may develop following exposure to an event or series of events of an extremely threatening or horrific nature, most commonly prolonged or repetitive events from which escape is difficult or impossible (e.g. torture, slavery, genocide campaigns, prolonged domestic violence, repeated childhood sexual or physical abuse). All diagnostic requirements for PTSD are met. In addition, Complex PTSD is characterised by severe and persistent 1) problems in affect regulation; 2) beliefs about oneself as diminished, defeated or worthless, accompanied by feelings of shame, guilt or failure related to the traumatic event; and 3) difficulties in sustaining relationships and in feeling close to others. These symptoms cause significant impairment in personal, family, social, educational, occupational or other important areas of functioning.

[1] https://en.wikipedia.org/wiki/DSM-5

[2] https://en.wikipedia.org/wiki/ICD-11

[3] QD85 Burnout https://icd.who.int/browse11/l-m/en#/http://id.who.int/icd/e...

[4] 6B40 Post traumatic stress disorder https://icd.who.int/browse11/l-m/en#/http://id.who.int/icd/e...

[5] 6B41 Complex post traumatic stress disorder https://icd.who.int/browse11/l-m/en#/http://id.who.int/icd/e...