Yes, you are eligible to be considered in PSU after having cleared GATE followed by clearance of AMIE examination through Graduate Engineer Trainee scheme. However, you have to satisfy the other parameters as well such as matching your age as per the requirement of Employers, minimum percentage of marks not below than 65 percent in both the sections A and B. In addition to these, you have to clear the written test organised by the Management and subsequent clearance of the oral - interview.
There are numerous organisations such as ONGC, IOCL, BCCL, NTPC etc, where special incentives are awarded to the aspirants having acquired high percentile in the GATE examination and they are given two additional increments in their pay- slabs. So, it would be a boon for an aspirant to have cleared the GATE test.
Lastly, with regard to your query that AMIE is not being regarded equivalent to Engineering - degree is false notion. For all recruitment - purposes, this degree is at par with graduate Engineering - degree since AMIE is approved by ministry of HRD and so wipe out your prevailing doubt. Prepare your written - test with confidence so that you are selected in a PSU followed by clearance of your oral - interview.