According to Wikipedia, the PDP-8/I was launched in 1968, while the VT100 wasn't available until August of 1978. While it is conceivable that an old PDP-8/I at some point was connected with a brand new VT100, it far more likely that early PDP-8/I's were connected to some brand of teletype machine like the Teletype Model 37.  By 1970 early VDUs like the Datapoint 3300 or DEC's own VT05 (I love the Jetson's futuristic look) were probably used.

If anyone in the Hackaday community has actual first hand knowledge of terminal usage I would be very curious to know. 

At any rate, I guess I get low marks for historical accuracy matching a VT100 with Oscar's PiDP-8/I reproduction. On the other hand, the DEC VT100 is probably one of the most iconic VDUs of all time, both in terms of its look, and the protocols (the emerging ANSI X3.64 standard) that it supported, to the point where VT100 emulators are ubiquitous even today.

Update

Jim Beatty was kind enough to share his experience with PDP-8 machines.

I cut my teeth on PDP-8s from about 1968-78.  Early on an ASR-33 teletype was the terminal of choice, at 110 baud.  Later there was a terminal called a Decwriter (I believe it was dot matrix).  Video terminals were a rarity until the mid-to late 70s.

ASR-33 on the left and Decwriter on the right.