As of 1.5.0, Tensor.print() seems to work to print type and shape info.
gdb) call t.print()
[CPUByteType [1, 10, 1, 10]]

To print full contents, it seems the form std::cout << Tensor << std::endl must be present in debugged C++ file first.  But you also have to call fflush(0) since gdb has trouble with std::endl in my test case.
A .gdbinit quick solution:
define ptensor
  call std::cout << $arg0
  call fflush(0)
end

(gdb) ptensor tensor
(1,1,.,.) =
  0  0  1  3  4  4  3  1  0  0
...

$4 = (std::ostream &) @0x55555597e740: <incomplete type>
[ CPUByteType{1,10,1,10} ]$5 = 0

But this prints the WHOLE tensor so only a partial solution.